Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/migrate/config/schema/migrate.data_types.schema.yml

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+# Basic data types for Migrate.
+
+migrate_plugin:
+  type: mapping
+  mapping:
+    plugin:
+      type: string
+      label: 'Plugin'
+
+migrate_destination:
+  type: migrate_plugin
+  label: 'Destination'
+
+migrate_source:
+  type: migrate_plugin
+  label: 'Source'
+  mapping:
+    constants:
+      type: ignore
+      label: 'Constants'
+
+# Base schema for migrate source plugins that extend
+# \Drupal\migrate\Plugin\migrate\source\SqlBase.
+migrate_source_sql:
+  type: migrate_source
+  mapping:
+    target:
+      type: string
+      label: 'The migration database target'
+
+migrate_load:
+  type: migrate_plugin
+  label: 'Load'

core/modules/migrate/config/schema/migrate.destination.schema.yml

@@ -0,0 +1,34 @@
+# Schema for the migrate destination plugins.
+
+migrate.destination.*:
+  type: migrate_destination
+  label: 'Default destination'
+  mapping:
+    no_stub:
+      type: boolean
+      label: 'Whether stubbing is allowed.'
+      default: false
+
+migrate.destination.config:
+  type: migrate_destination
+  label: 'Config'
+  mapping:
+    config_name:
+      type: string
+      label: 'Configuration name'
+
+migrate.destination.entity:user:
+  type: migrate_destination
+  label: 'User'
+  mapping:
+    md5_passwords:
+      type: boolean
+      label: 'Passwords'
+
+migrate.destination.entity:file:
+  type: migrate_destination
+  label: 'Picture'
+  mapping:
+    source_path_property:
+      type: string
+      label: 'Source path'

core/modules/migrate/config/schema/migrate.load.schema.yml

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+# Schema for the migrate load plugins.
+
+migrate.load.*:
+  type: migrate_load
+  label: 'Default load'
+
+migrate.load.drupal_entity:
+  type: migrate_load
+  label: 'Default source'
+  mapping:
+    bundle_migration:
+      type: string
+      label: 'Bundle migration'
+
+migrate.load.d6_term_node:
+  type: migrate_load
+  label: 'Default source'
+  mapping:
+    bundle_migration:
+      type: string
+      label: 'Bundle migration'

core/modules/migrate/config/schema/migrate.schema.yml

@@ -0,0 +1,46 @@
+# Schema for the configuration files of the Migrate module.
+
+migrate.migration.*:
+  type: config_entity
+  label: 'Migration'
+  mapping:
+    id:
+      type: string
+      label: 'ID'
+    migration_tags:
+      type: sequence
+      label: 'Migration Tags'
+      sequence:
+        type: string
+        label: 'Tag'
+    label:
+      type: label
+      label: 'Label'
+    load:
+      type: migrate.load.[plugin]
+      label: 'Source'
+    source:
+      type: migrate.source.[plugin]
+      label: 'Source'
+    process:
+      type: ignore
+      label: 'Process'
+    destination:
+      type: migrate.destination.[plugin]
+      label: 'Destination'
+    migration_dependencies:
+      type: mapping
+      label: 'Dependencies'
+      mapping:
+        required:
+          type: sequence
+          label: 'Required dependencies'
+          sequence:
+            type: string
+            label: 'Dependency'
+        optional:
+          type: sequence
+          label: 'Optional dependencies'
+          sequence:
+            type: string
+            label: 'Dependency'

core/modules/migrate/config/schema/migrate.source.schema.yml

@@ -0,0 +1,13 @@
+# Schema for the migrate source plugins.
+
+migrate.source.*:
+  type: migrate_source
+  label: 'Default source'
+
+migrate.source.empty:
+  type: migrate_source_sql
+  label: 'Empty source'
+  mapping:
+    provider:
+      type: string
+      label: 'Provider'

core/modules/migrate/migrate.api.php

@@ -0,0 +1,131 @@
+<?php
+
+/**
+ * @file
+ * Hooks provided by the Migrate module.
+ */
+
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Plugin\MigrateSourceInterface;
+use Drupal\migrate\Row;
+
+/**
+ * @defgroup migration Migration API
+ * @{
+ * Overview of the Migration API, which migrates data into Drupal.
+ *
+ * @section overview Overview of migration
+ * Migration is an
+ * @link http://wikipedia.org/wiki/Extract,_transform,_load Extract, Transform, Load @endlink
+ * (ETL) process. For historical reasons, in the Drupal migration tool the
+ * extract phase is called "source", the transform phase is called "process",
+ * and the load phase is called "destination".
+ *
+ * Source, process, and destination phases are each provided by plugins. Source
+ * plugins extract data from a data source in "rows", containing "properties".
+ * Each row is handed off to one or more series of process plugins, where each
+ * series operates to transform the row data into one result property. After all
+ * the properties are processed, the resulting row is handed off to a
+ * destination plugin, which saves the data.
+ *
+ * The Migrate module provides process plugins for common operations (setting
+ * default values, mapping values, etc.), and destination plugins for Drupal
+ * core objects (configuration, entity, URL alias, etc.). The Migrate Drupal
+ * module provides source plugins to extract data from various versions of
+ * Drupal. Custom and contributed modules can provide additional plugins; see
+ * the @link plugin_api Plugin API topic @endlink for generic information about
+ * providing plugins, and sections below for details about the plugin types.
+ *
+ * The configuration of migrations is stored in configuration entities, which
+ * list the IDs and configurations of the plugins that are involved. See
+ * @ref sec_entity below for details. To migrate an entire site, you'll need to
+ * create a migration manifest; see @ref sec_manifest for details.
+ *
+ * https://www.drupal.org/node/2127611 has more complete information on the
+ * Migration API, including information on load plugins, which are only used
+ * in Drupal 6 migration.
+ *
+ * @section sec_source Source plugins
+ * Migration source plugins implement
+ * \Drupal\migrate\Plugin\MigrateSourceInterface and usually extend
+ * \Drupal\migrate\Plugin\migrate\source\SourcePluginBase. They are annotated
+ * with \Drupal\migrate\Annotation\MigrateSource annotation, and must be in
+ * namespace subdirectory Plugin\migrate\source under the namespace of the
+ * module that defines them. Migration source plugins are managed by the
+ * \Drupal\migrate\Plugin\MigratePluginManager class.
+ *
+ * @section sec_process Process plugins
+ * Migration process plugins implement
+ * \Drupal\migrate\Plugin\MigrateProcessInterface and usually extend
+ * \Drupal\migrate\ProcessPluginBase. They are annotated
+ * with \Drupal\migrate\Annotation\MigrateProcessPlugin annotation, and must be
+ * in namespace subdirectory Plugin\migrate\process under the namespace of the
+ * module that defines them. Migration process plugins are managed by the
+ * \Drupal\migrate\Plugin\MigratePluginManager class.
+ *
+ * @section sec_destination Destination plugins
+ * Migration destination plugins implement
+ * \Drupal\migrate\Plugin\MigrateDestinationInterface and usually extend
+ * \Drupal\migrate\Plugin\migrate\destination\DestinationBase. They are
+ * annotated with \Drupal\migrate\Annotation\MigrateDestination annotation, and
+ * must be in namespace subdirectory Plugin\migrate\destination under the
+ * namespace of the module that defines them. Migration destination plugins
+ * are managed by the
+ * \Drupal\migrate\Plugin\MigrateDestinationPluginManager class.
+ *
+ * @section sec_entity Migration configuration entities
+ * The definition of how to migrate each type of data is stored in configuration
+ * entities. The migration configuration entity class is
+ * \Drupal\migrate\Entity\Migration, with interface
+ * \Drupal\migrate\Entity\MigrationInterface; the configuration schema can be
+ * found in the migrate.schema.yml file. Migration configuration consists of IDs
+ * and configuration for the source, process, and destination plugins, as well
+ * as information on dependencies. Process configuration consists of sections,
+ * each of which defines the series of process plugins needed for one
+ * destination property. You can find examples of migration configuration files
+ * in the core/modules/migrate_drupal/config/install directory.
+ *
+ * @section sec_manifest Migration manifests
+ * You can run a migration with the "drush migrate-manifest" command, providing
+ * a migration manifest file. This file lists the configuration names of the
+ * migrations you want to execute, as well as any dependencies they have (you
+ * can find these in the "migration_dependencies" sections of the individual
+ * configuration files). For example, to migrate blocks from a Drupal 6 site,
+ * you would list:
+ * @code
+ * # Migrate blocks from Drupal 6 to 8
+ * - d6_filter_format
+ * - d6_custom_block
+ * - d6_block
+ * @endcode
+ * @}
+ */
+
+/**
+ * @addtogroup hooks
+ * @{
+ */
+
+/**
+ * Allows adding data to a row before processing it.
+ *
+ * For example, filter module used to store filter format settings in the
+ * variables table which now needs to be inside the filter format config
+ * file. So, it needs to be added here.
+ *
+ * hook_migrate_MIGRATION_ID_prepare_row() is also available.
+ *
+ * @ingroup migration
+ */
+function hook_migrate_prepare_row(Row $row, MigrateSourceInterface $source, MigrationInterface $migration) {
+  if ($migration->id() == 'd6_filter_formats') {
+    $value = $source->getDatabase()->query('SELECT value FROM {variable} WHERE name = :name', array(':name' => 'mymodule_filter_foo_' . $row->getSourceProperty('format')))->fetchField();
+    if ($value) {
+      $row->setSourceProperty('settings:mymodule:foo', unserialize($value));
+    }
+  }
+}
+
+/**
+ * @} End of "addtogroup hooks".
+ */

core/modules/migrate/migrate.info.yml

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+name: Migrate
+type: module
+description: 'Handles migrations'
+package: Core
+version: VERSION
+core: 8.x
+;configure: admin/structure/migrate

core/modules/migrate/migrate.module

@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * @file
+ * Provides the Migrate API.
+ */
+
+use Drupal\Core\Routing\RouteMatchInterface;
+
+/**
+ * Implements hook_help().
+ */
+function migrate_help($route_name, RouteMatchInterface $route_match) {
+  switch ($route_name) {
+    case 'help.page.migrate':
+      $output = '<h3>' . t('About') . '</h3>';
+      $output .= '<p>';
+      $output .= t('The Migrate module provides a framework for migrating data, usually from an external source into your site. It does not provide a user interface. For more information, see the <a href="!migrate">online documentation for the Migrate module</a>.', array('!migrate' => 'https://www.drupal.org/documentation/modules/migrate'));
+      $output .= '</p>';
+      return $output;
+  }
+}

core/modules/migrate/migrate.services.yml

@@ -0,0 +1,22 @@
+services:
+  cache.migrate:
+    class: Drupal\Core\Cache\CacheBackendInterface
+    tags:
+      - { name: cache.bin }
+    factory: cache_factory:get
+    arguments: [migrate]
+  plugin.manager.migrate.source:
+    class: Drupal\migrate\Plugin\MigratePluginManager
+    arguments: [source, '@container.namespaces', '@cache.discovery', '@module_handler', 'Drupal\migrate\Annotation\MigrateSource']
+  plugin.manager.migrate.process:
+    class: Drupal\migrate\Plugin\MigratePluginManager
+    arguments: [process, '@container.namespaces', '@cache.discovery', '@module_handler', 'Drupal\migrate\Annotation\MigrateProcessPlugin']
+  plugin.manager.migrate.destination:
+    class: Drupal\migrate\Plugin\MigrateDestinationPluginManager
+    arguments: [destination, '@container.namespaces', '@cache.discovery', '@module_handler', '@entity.manager']
+  plugin.manager.migrate.id_map:
+    class: Drupal\migrate\Plugin\MigratePluginManager
+    arguments: [id_map, '@container.namespaces', '@cache.discovery', '@module_handler']
+  password_migrate:
+    class: Drupal\migrate\MigratePassword
+    arguments: ['@password_original']

core/modules/migrate/src/Annotation/MigrateDestination.php

@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Annotation\MigrateDestination.
+ */
+
+namespace Drupal\migrate\Annotation;
+
+use Drupal\Component\Annotation\Plugin;
+
+/**
+ * Defines a migration destination plugin annotation object.
+ *
+ * Plugin Namespace: Plugin\migrate\destination
+ *
+ * For a working example, see
+ * \Drupal\migrate\Plugin\migrate\destination\UrlAlias
+ *
+ * @see \Drupal\migrate\Plugin\MigrateDestinationInterface
+ * @see \Drupal\migrate\Plugin\destination\DestinationBase
+ * @see \Drupal\migrate\Plugin\MigrateDestinationPluginManager
+ * @see \Drupal\migrate\Annotation\MigrateSource
+ * @see \Drupal\migrate\Annotation\MigrateProcessPlugin
+ * @see plugin_api
+ *
+ * @ingroup migration
+ *
+ * @Annotation
+ */
+class MigrateDestination extends Plugin {
+
+  /**
+   * A unique identifier for the process plugin.
+   *
+   * @var string
+   */
+  public $id;
+
+  /**
+   * Whether requirements are met.
+   *
+   * If TRUE and a 'provider' key is present in the annotation then the
+   * default destination plugin manager will set this to FALSE if the
+   * provider (module/theme) doesn't exist.
+   *
+   * @var bool
+   */
+  public $requirements_met = TRUE;
+
+  /**
+   * A class to make the plugin derivative aware.
+   *
+   * @var string
+   *
+   * @see \Drupal\Component\Plugin\Discovery\DerivativeDiscoveryDecorator
+   */
+  public $derivative;
+
+}

core/modules/migrate/src/Annotation/MigrateProcessPlugin.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Annotation\MigrateProcessPlugin.
+ */
+
+namespace Drupal\migrate\Annotation;
+
+use Drupal\Component\Annotation\Plugin;
+
+/**
+ * Defines a migration process plugin annotation object.
+ *
+ * Plugin Namespace: Plugin\migrate\process
+ *
+ * For a working example, see
+ * \Drupal\migrate\Plugin\migrate\process\DefaultValue
+ *
+ * @see \Drupal\migrate\Plugin\MigratePluginManager
+ * @see \Drupal\migrate\Plugin\MigrateProcessInterface
+ * @see \Drupal\migrate\ProcessPluginBase
+ * @see \Drupal\migrate\Annotation\MigrateSource
+ * @see \Drupal\migrate\Annotation\MigrateDestination
+ * @see plugin_api
+ *
+ * @ingroup migration
+ *
+ * @Annotation
+ */
+class MigrateProcessPlugin extends Plugin {
+
+  /**
+   * A unique identifier for the process plugin.
+   *
+   * @var string
+   */
+  public $id;
+
+  /**
+   * Whether the plugin handles multiples itself.
+   *
+   * Typically these plugins will expect an array as input and iterate over it
+   * themselves, changing the whole array. For example the 'iterator' and the
+   * 'flatten' plugins. If the plugin only need to change a single value it
+   * can skip setting this attribute and let
+   * \Drupal\migrate\MigrateExecutable::processRow() handle the iteration.
+   *
+   * @var bool (optional)
+   */
+  public $handle_multiples = FALSE;
+}

core/modules/migrate/src/Annotation/MigrateSource.php

@@ -0,0 +1,48 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Annotation\MigrateSource.
+ */
+
+namespace Drupal\migrate\Annotation;
+
+use Drupal\Component\Annotation\Plugin;
+
+/**
+ * Defines a migration source plugin annotation object.
+ *
+ * Plugin Namespace: Plugin\migrate\source
+ *
+ * For a working example, check
+ * \Drupal\migrate\Plugin\migrate\source\EmptySource
+ * \Drupal\migrate_drupal\Plugin\migrate\source\UrlAlias
+ *
+ * @see \Drupal\migrate\Plugin\MigratePluginManager
+ * @see \Drupal\migrate\Plugin\MigrateSourceInterface
+ * @see \Drupal\migrate\Plugin\migrate\source\SourcePluginBase
+ * @see \Drupal\migrate\Annotation\MigrateProcessPlugin
+ * @see \Drupal\migrate\Annotation\MigrateDestination
+ * @see plugin_api
+ *
+ * @ingroup migration
+ *
+ * @Annotation
+ */
+class MigrateSource extends Plugin {
+
+  /**
+   * A unique identifier for the process plugin.
+   *
+   * @var string
+   */
+  public $id;
+
+  /**
+   * Whether requirements are met.
+   *
+   * @var bool
+   */
+  public $requirements_met = TRUE;
+
+}

core/modules/migrate/src/Entity/Migration.php

@@ -0,0 +1,537 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Entity\Migration.
+ */
+
+namespace Drupal\migrate\Entity;
+
+use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Core\Config\Entity\ConfigEntityBase;
+use Drupal\migrate\Exception\RequirementsException;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\MigrateSkipRowException;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+use Drupal\migrate\Plugin\RequirementsInterface;
+use Drupal\Component\Utility\NestedArray;
+
+/**
+ * Defines the Migration entity.
+ *
+ * The migration entity stores the information about a single migration, like
+ * the source, process and destination plugins.
+ *
+ * @ConfigEntityType(
+ *   id = "migration",
+ *   label = @Translation("Migration"),
+ *   module = "migrate",
+ *   handlers = {
+ *     "storage" = "Drupal\migrate\MigrationStorage"
+ *   },
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "label" = "label",
+ *     "weight" = "weight"
+ *   }
+ * )
+ */
+class Migration extends ConfigEntityBase implements MigrationInterface, RequirementsInterface {
+
+  /**
+   * The migration ID (machine name).
+   *
+   * @var string
+   */
+  protected $id;
+
+  /**
+   * The human-readable label for the migration.
+   *
+   * @var string
+   */
+  protected $label;
+
+  /**
+   * The plugin ID for the row.
+   *
+   * @var string
+   */
+  protected $row;
+
+  /**
+   * The source configuration, with at least a 'plugin' key.
+   *
+   * Used to initialize the $sourcePlugin.
+   *
+   * @var array
+   */
+  protected $source;
+
+  /**
+   * The source plugin.
+   *
+   * @var \Drupal\migrate\Plugin\MigrateSourceInterface
+   */
+  protected $sourcePlugin;
+
+  /**
+   * The configuration describing the process plugins.
+   *
+   * This is a strictly internal property and should not returned to calling
+   * code, use getProcess() instead.
+   *
+   * @var array
+   */
+  protected $process;
+
+  /**
+   * The configuration describing the load plugins.
+   *
+   * @var array
+   */
+  protected $load;
+
+  /**
+   * The cached process plugins.
+   *
+   * @var array
+   */
+  protected $processPlugins = [];
+
+  /**
+   * The destination configuration, with at least a 'plugin' key.
+   *
+   * Used to initialize $destinationPlugin.
+   *
+   * @var array
+   */
+  protected $destination;
+
+  /**
+   * The destination plugin.
+   *
+   * @var \Drupal\migrate\Plugin\MigrateDestinationInterface
+   */
+  protected $destinationPlugin;
+
+  /**
+   * The identifier map data.
+   *
+   * Used to initialize $idMapPlugin.
+   *
+   * @var string
+   */
+  protected $idMap = [];
+
+  /**
+   * The identifier map.
+   *
+   * @var \Drupal\migrate\Plugin\MigrateIdMapInterface
+   */
+  protected $idMapPlugin;
+
+  /**
+   * The source identifiers.
+   *
+   * An array of source identifiers: the keys are the name of the properties,
+   * the values are dependent on the ID map plugin.
+   *
+   * @var array
+   */
+  protected $sourceIds = [];
+
+  /**
+   * The destination identifiers.
+   *
+   * An array of destination identifiers: the keys are the name of the
+   * properties, the values are dependent on the ID map plugin.
+   *
+   * @var array
+   */
+  protected $destinationIds = [];
+
+  /**
+   * Information on the high water mark.
+   *
+   * @var array
+   */
+  protected $highWaterProperty;
+
+  /**
+   * Indicate whether the primary system of record for this migration is the
+   * source, or the destination (Drupal). In the source case, migration of
+   * an existing object will completely replace the Drupal object with data from
+   * the source side. In the destination case, the existing Drupal object will
+   * be loaded, then changes from the source applied; also, rollback will not be
+   * supported.
+   *
+   * @var string
+   */
+  protected $systemOfRecord = self::SOURCE;
+
+  /**
+   * Specify value of source_row_status for current map row. Usually set by
+   * MigrateFieldHandler implementations.
+   *
+   * @var int
+   */
+  protected $sourceRowStatus = MigrateIdMapInterface::STATUS_IMPORTED;
+
+  /**
+   * @var \Drupal\Core\KeyValueStore\KeyValueStoreInterface
+   */
+  protected $highWaterStorage;
+
+  /**
+   * Track time of last import if TRUE.
+   *
+   * @var bool
+   */
+  protected $trackLastImported = FALSE;
+
+  /**
+   * These migrations must be already executed before this migration can run.
+   *
+   * @var array
+   */
+  protected $requirements = [];
+
+  /**
+   * These migrations, if run, must be executed before this migration.
+   *
+   * These are different from the configuration dependencies. Migration
+   * dependencies are only used to store relationships between migrations.
+   *
+   * The migration_dependencies value is structured like this:
+   * @code
+   * array(
+   *   'required' => array(
+   *     // An array of migration IDs that must be run before this migration.
+   *   ),
+   *   'optional' => array(
+   *     // An array of migration IDs that, if they exist, must be run before
+   *     // this migration.
+   *   ),
+   * );
+   * @endcode
+   *
+   * @var array
+   */
+  protected $migration_dependencies = [];
+
+  /**
+   * The migration's configuration dependencies.
+   *
+   * These store any dependencies on modules or other configuration (including
+   * other migrations) that must be available before the migration can be
+   * created.
+   *
+   * @see \Drupal\Core\Config\Entity\ConfigDependencyManager
+   *
+   * @var array
+   */
+  protected $dependencies = [];
+
+  /**
+   * The entity manager.
+   *
+   * @var \Drupal\Core\Entity\EntityManagerInterface
+   */
+  protected $entityManager;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getSourcePlugin() {
+    if (!isset($this->sourcePlugin)) {
+      $this->sourcePlugin = \Drupal::service('plugin.manager.migrate.source')->createInstance($this->source['plugin'], $this->source, $this);
+    }
+    return $this->sourcePlugin;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getProcessPlugins(array $process = NULL) {
+    if (!isset($process)) {
+      $process = $this->process;
+    }
+    $index = serialize($process);
+    if (!isset($this->processPlugins[$index])) {
+      $this->processPlugins[$index] = array();
+      foreach ($this->getProcessNormalized($process) as $property => $configurations) {
+        $this->processPlugins[$index][$property] = array();
+        foreach ($configurations as $configuration) {
+          if (isset($configuration['source'])) {
+            $this->processPlugins[$index][$property][] = \Drupal::service('plugin.manager.migrate.process')->createInstance('get', $configuration, $this);
+          }
+          // Get is already handled.
+          if ($configuration['plugin'] != 'get') {
+            $this->processPlugins[$index][$property][] = \Drupal::service('plugin.manager.migrate.process')->createInstance($configuration['plugin'], $configuration, $this);
+          }
+          if (!$this->processPlugins[$index][$property]) {
+            throw new MigrateException("Invalid process configuration for $property");
+          }
+        }
+      }
+    }
+    return $this->processPlugins[$index];
+  }
+
+  /**
+   * Resolve shorthands into a list of plugin configurations.
+   *
+   * @param array $process
+   *   A process configuration array.
+   *
+   * @return array
+   *   The normalized process configuration.
+   */
+  protected function getProcessNormalized(array $process) {
+    $normalized_configurations = array();
+    foreach ($process as $destination => $configuration) {
+      if (is_string($configuration)) {
+        $configuration = array(
+          'plugin' => 'get',
+          'source' => $configuration,
+        );
+      }
+      if (isset($configuration['plugin'])) {
+        $configuration = array($configuration);
+      }
+      $normalized_configurations[$destination] = $configuration;
+    }
+    return $normalized_configurations;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDestinationPlugin($stub_being_requested = FALSE) {
+    if (!isset($this->destinationPlugin)) {
+      if ($stub_being_requested && !empty($this->destination['no_stub'])) {
+        throw new MigrateSkipRowException;
+      }
+      $this->destinationPlugin = \Drupal::service('plugin.manager.migrate.destination')->createInstance($this->destination['plugin'], $this->destination, $this);
+    }
+    return $this->destinationPlugin;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIdMap() {
+    if (!isset($this->idMapPlugin)) {
+      $configuration = $this->idMap;
+      $plugin = isset($configuration['plugin']) ? $configuration['plugin'] : 'sql';
+      $this->idMapPlugin = \Drupal::service('plugin.manager.migrate.id_map')->createInstance($plugin, $configuration, $this);
+    }
+    return $this->idMapPlugin;
+  }
+
+  /**
+   * Get the high water storage object.
+   *
+   * @return \Drupal\Core\KeyValueStore\KeyValueStoreInterface
+   *   The storage object.
+   */
+  protected function getHighWaterStorage() {
+    if (!isset($this->highWaterStorage)) {
+      $this->highWaterStorage = \Drupal::keyValue('migrate:high_water');
+    }
+    return $this->highWaterStorage;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getHighWater() {
+    return $this->getHighWaterStorage()->get($this->id());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function saveHighWater($high_water) {
+    $this->getHighWaterStorage()->set($this->id(), $high_water);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function checkRequirements() {
+    // Check whether the current migration source and destination plugin
+    // requirements are met or not.
+    if ($this->getSourcePlugin() instanceof RequirementsInterface) {
+      $this->getSourcePlugin()->checkRequirements();
+    }
+    if ($this->getDestinationPlugin() instanceof RequirementsInterface) {
+      $this->getDestinationPlugin()->checkRequirements();
+    }
+
+    /** @var \Drupal\migrate\Entity\MigrationInterface[] $required_migrations */
+    $required_migrations = $this->getEntityManager()->getStorage('migration')->loadMultiple($this->requirements);
+
+    $missing_migrations = array_diff($this->requirements, array_keys($required_migrations));
+    // Check if the dependencies are in good shape.
+    foreach ($required_migrations as $migration_id => $required_migration) {
+      if (!$required_migration->isComplete()) {
+        $missing_migrations[] = $migration_id;
+      }
+    }
+    if ($missing_migrations) {
+      throw new RequirementsException(SafeMarkup::format('Missing migrations @requirements.', ['@requirements' => implode(', ', $missing_migrations)]), ['requirements' => $missing_migrations]);
+    }
+  }
+
+  /**
+   * Get the entity manager.
+   *
+   * @return \Drupal\Core\Entity\EntityManagerInterface
+   *   The entity manager.
+   */
+  protected function getEntityManager() {
+    if (!isset($this->entityManager)) {
+      $this->entityManager = \Drupal::entityManager();
+    }
+    return $this->entityManager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setMigrationResult($result) {
+    $migrate_result_store = \Drupal::keyValue('migrate_result');
+    $migrate_result_store->set($this->id(), $result);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMigrationResult() {
+    $migrate_result_store = \Drupal::keyValue('migrate_result');
+    return $migrate_result_store->get($this->id(), static::RESULT_INCOMPLETE);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isComplete() {
+    return $this->getMigrationResult() === static::RESULT_COMPLETED;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function set($property_name, $value) {
+    if ($property_name == 'source') {
+      // Invalidate the source plugin.
+      unset($this->sourcePlugin);
+    }
+    return parent::set($property_name, $value);
+  }
+
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getProcess() {
+    return $this->getProcessNormalized($this->process);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setProcess(array $process) {
+    $this->process = $process;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setProcessOfProperty($property, $process_of_property) {
+    $this->process[$property] = $process_of_property;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function mergeProcessOfProperty($property, array $process_of_property) {
+    // If we already have a process value then merge the incoming process array
+    //otherwise simply set it.
+    $current_process = $this->getProcess();
+    if (isset($current_process[$property])) {
+      $this->process = NestedArray::mergeDeepArray([$current_process, $this->getProcessNormalized([$property => $process_of_property])], TRUE);
+    }
+    else {
+      $this->setProcessOfProperty($property, $process_of_property);
+    }
+
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getSystemOfRecord() {
+    return $this->systemOfRecord;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setSystemOfRecord($system_of_record) {
+    $this->systemOfRecord = $system_of_record;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isTrackLastImported() {
+    return $this->trackLastImported;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setTrackLastImported($track_last_imported) {
+    $this->trackLastImported = (bool) $track_last_imported;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMigrationDependencies() {
+    return $this->migration_dependencies + ['required' => [], 'optional' => []];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function trustData() {
+    // Migrations cannot be trusted since they are often written by hand and not
+    // through a UI.
+    $this->trustedData = FALSE;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function calculateDependencies() {
+    parent::calculateDependencies();
+    $this->calculatePluginDependencies($this->getSourcePlugin());
+    $this->calculatePluginDependencies($this->getDestinationPlugin());
+    // Add dependencies on required migration dependencies.
+    foreach ($this->getMigrationDependencies()['required'] as $dependency) {
+      $this->addDependency('config', $this->getEntityType()->getConfigPrefix() . '.' . $dependency);
+    }
+
+    return $this->dependencies;
+  }
+}

core/modules/migrate/src/Entity/MigrationInterface.php

@@ -0,0 +1,286 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Entity\MigrationInterface.
+ */
+
+namespace Drupal\migrate\Entity;
+
+use Drupal\Core\Config\Entity\ConfigEntityInterface;
+
+/**
+ * Interface for migrations.
+ */
+interface MigrationInterface extends ConfigEntityInterface {
+
+  /**
+   * A constant used for systemOfRecord.
+   */
+  const SOURCE = 'source';
+
+  /**
+   * A constant used for systemOfRecord.
+   */
+  const DESTINATION = 'destination';
+
+  /**
+   * The migration is currently not running.
+   */
+  const STATUS_IDLE = 0;
+
+  /**
+   * The migration is currently importing.
+   */
+  const STATUS_IMPORTING = 1;
+
+  /**
+   * The migration is currently being rolled back.
+   */
+  const STATUS_ROLLING_BACK = 2;
+
+  /**
+   * The migration is being stopped.
+   */
+  const STATUS_STOPPING = 3;
+
+  /**
+   * The migration has been disabled.
+   */
+  const STATUS_DISABLED = 4;
+
+  /**
+   * Migration error.
+   */
+  const MESSAGE_ERROR = 1;
+
+  /**
+   * Migration warning.
+   */
+  const MESSAGE_WARNING = 2;
+
+  /**
+   * Migration notice.
+   */
+  const MESSAGE_NOTICE = 3;
+
+  /**
+   * Migration info.
+   */
+  const MESSAGE_INFORMATIONAL = 4;
+
+  /**
+   * All records have been processed.
+   */
+  const RESULT_COMPLETED = 1;
+
+  /**
+   * The process has stopped itself (e.g., the memory limit is approaching).
+   */
+  const RESULT_INCOMPLETE = 2;
+
+  /**
+   * The process was stopped externally (e.g., via drush migrate-stop).
+   */
+  const RESULT_STOPPED = 3;
+
+  /**
+   * The process had a fatal error.
+   */
+  const RESULT_FAILED = 4;
+
+  /**
+   * Dependencies are unfulfilled - skip the process.
+   */
+  const RESULT_SKIPPED = 5;
+
+  /**
+   * This migration is disabled, skipping.
+   */
+  const RESULT_DISABLED = 6;
+
+  /**
+   * Returns the initialized source plugin.
+   *
+   * @return \Drupal\migrate\Plugin\MigrateSourceInterface
+   *   The source plugin.
+   */
+  public function getSourcePlugin();
+
+  /**
+   * Returns the process plugins.
+   *
+   * @param array $process
+   *   A process configuration array.
+   *
+   * @return \Drupal\migrate\Plugin\MigrateProcessInterface[][]
+   *   An associative array. The keys are the destination property names. Values
+   *   are process pipelines. Each pipeline contains an array of plugins.
+   */
+  public function getProcessPlugins(array $process = NULL);
+
+  /**
+   * Returns the initialized destination plugin.
+   *
+   * @param bool $stub_being_requested
+   *  TRUE to indicate that this destination will be asked to construct a stub.
+   *
+   * @return \Drupal\migrate\Plugin\MigrateDestinationInterface
+   *   The destination plugin.
+   */
+  public function getDestinationPlugin($stub_being_requested = FALSE);
+
+  /**
+   * Returns the initialized id_map plugin.
+   *
+   * @return \Drupal\migrate\Plugin\MigrateIdMapInterface
+   *   The ID map.
+   */
+  public function getIdMap();
+
+  /**
+   * The current value of the high water mark.
+   *
+   * The high water mark defines a timestamp stating the time the import was last
+   * run. If the mark is set, only content with a higher timestamp will be
+   * imported.
+   *
+   * @return int
+   *   A Unix timestamp representing the high water mark.
+   */
+  public function getHighWater();
+
+  /**
+   * Save the new high water mark.
+   *
+   * @param int $high_water
+   *   The high water timestamp.
+   */
+  public function saveHighWater($high_water);
+
+  /**
+   * Check if this migration is complete.
+   *
+   * @return bool
+   *   TRUE if this migration is complete otherwise FALSE.
+   */
+  public function isComplete();
+
+  /**
+   * Set the migration result.
+   *
+   * @param int $result
+   *   One of the RESULT_* constants.
+   */
+  public function setMigrationResult($result);
+
+  /**
+   * Get the current migration result.
+   *
+   * @return int
+   *   The current migration result. Defaults to RESULT_INCOMPLETE.
+   */
+  public function getMigrationResult();
+
+  /**
+   * Get the normalized process pipeline configuration describing the process
+   * plugins.
+   *
+   * The process configuration is always normalized. All shorthand processing
+   * will be expanded into their full representations.
+   *
+   * @see https://www.drupal.org/node/2129651#get-shorthand
+   *
+   * @return array
+   *   The normalized configuration describing the process plugins.
+   */
+  public function getProcess();
+
+  /**
+   * Allows you to override the entire process configuration.
+   *
+   * @param array $process
+   *   The entire process pipeline configuration describing the process plugins.
+   *
+   * @return $this
+   */
+  public function setProcess(array $process);
+
+  /**
+   * Set the process pipeline configuration for an individual destination field.
+   *
+   * This method allows you to set the process pipeline configuration for a
+   * single property within the full process pipeline configuration.
+   *
+   * @param string $property
+   *   The property of which to set the process pipeline configuration.
+   * @param mixed $process_of_property
+   *   The process pipeline configuration to be set for this property.
+   *
+   * @return $this
+   *   The migration entity.
+   */
+  public function setProcessOfProperty($property, $process_of_property);
+
+  /**
+   * Merge the process pipeline configuration for a single property.
+   *
+   * @param string $property
+   *   The property of which to merge the passed in process pipeline
+   * configuration.
+   * @param array $process_of_property
+   *   The process pipeline configuration to be merged with the existing process
+   * pipeline configuration.
+   *
+   * @return $this
+   *   The migration entity.
+   *
+   * @see Drupal\migrate_drupal\Plugin\migrate\load\LoadEntity::processLinkField().
+   */
+  public function mergeProcessOfProperty($property, array $process_of_property);
+
+  /**
+   * Get the current system of record of the migration.
+   *
+   * @return string
+   *   The current system of record of the migration.
+   */
+  public function getSystemOfRecord();
+
+  /**
+   * Set the system of record for the migration.
+   *
+   * @param string $system_of_record
+   *   The system of record of the migration.
+   *
+   * @return $this
+   */
+  public function setSystemOfRecord($system_of_record);
+
+  /**
+   * Checks if the migration should track time of last import.
+   *
+   * @return bool
+   *   TRUE if the migration is tracking last import time.
+   */
+  public function isTrackLastImported();
+
+  /**
+   * Set if the migration should track time of last import.
+   *
+   * @param bool $track_last_imported
+   *   Boolean value to indicate if the migration should track last import time.
+   *
+   * @return $this
+   */
+  public function setTrackLastImported($track_last_imported);
+
+  /**
+   * Get the dependencies for this migration.
+   *
+   * @return array
+   *   The dependencies for this migrations.
+   */
+  public function getMigrationDependencies();
+
+}

core/modules/migrate/src/Exception/RequirementsException.php

@@ -0,0 +1,70 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Exception\RequirementsException.
+ */
+
+namespace Drupal\migrate\Exception;
+
+use Exception;
+
+/**
+ * Defines an
+ *
+ * @see \Drupal\migrate\Plugin\RequirementsInterface
+ */
+class RequirementsException extends \RuntimeException {
+
+  /**
+   * The missing requirements.
+   *
+   * @var array
+   */
+  protected $requirements;
+
+  /**
+   * Constructs a new RequirementsException instance.
+   *
+   * @param string $message
+   *   (optional) The Exception message to throw.
+   * @param array $requirements
+   *   (optional) The missing requirements.
+   * @param int $code
+   *   (optional) The Exception code.
+   * @param \Exception $previous
+   *   (optional) The previous exception used for the exception chaining.
+   */
+  public function __construct($message = "", array $requirements = [], $code = 0, Exception $previous = NULL) {
+    parent::__construct($message, $code, $previous);
+
+    $this->requirements = $requirements;
+  }
+
+  /**
+   * Get an array of requirements.
+   *
+   * @return array
+   *   The requirements.
+   */
+  public function getRequirements() {
+    return $this->requirements;
+  }
+
+  /**
+   * Get the requirements as a string.
+   *
+   * @return string
+   *   A formatted requirements string.
+   */
+  public function getRequirementsString() {
+    $output = '';
+    foreach ($this->requirements as $requirement_type => $requirements) {
+      foreach ($requirements as $value) {
+        $output .= "$requirement_type: $value. ";
+      }
+    }
+    return trim($output);
+  }
+
+}

core/modules/migrate/src/MigrateBuildDependencyInterface.php

@@ -0,0 +1,25 @@
+<?php
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateBuildDependencyInterface.
+ */
+
+namespace Drupal\migrate;
+
+
+interface MigrateBuildDependencyInterface {
+
+  /**
+   * Builds a dependency tree for the migrations and set their order.
+   *
+   * @param \Drupal\migrate\Entity\MigrationInterface[] $migrations
+   *   Array of loaded migrations with their declared dependencies.
+   * @param array $dynamic_ids
+   *   Keys are dynamic ids (for example node:*) values are a list of loaded
+   *   migration ids (for example node:page, node:article).
+   *
+   * @return array
+   *   An array of migrations.
+   */
+  public function buildDependencyMigration(array $migrations, array $dynamic_ids);
+}

core/modules/migrate/src/MigrateException.php

@@ -0,0 +1,77 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateException.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+
+/**
+ * Defines the migrate exception class.
+ */
+class MigrateException extends \Exception {
+
+  /**
+   * The level of the error being reported.
+   *
+   * The value is a Migration::MESSAGE_* constant.
+   *
+   * @var int
+   */
+  protected $level;
+
+  /**
+   * The status to record in the map table for the current item.
+   *
+   * The value is a MigrateMap::STATUS_* constant.
+   *
+   * @var int
+   */
+  protected $status;
+
+  /**
+   * Constructs a MigrateException object.
+   *
+   * @param string $message
+   *   The message for the exception.
+   * @param int $code
+   *   The Exception code.
+   * @param \Exception $previous
+   *   The previous exception used for the exception chaining.
+   * @param int $level
+   *   The level of the error, a Migration::MESSAGE_* constant.
+   * @param int $status
+   *   The status of the item for the map table, a MigrateMap::STATUS_*
+   *   constant.
+   */
+  public function __construct($message = NULL, $code = 0, \Exception $previous = NULL, $level = MigrationInterface::MESSAGE_ERROR, $status = MigrateIdMapInterface::STATUS_FAILED) {
+    $this->level = $level;
+    $this->status = $status;
+    parent::__construct($message);
+  }
+
+  /**
+   * Gets the level.
+   *
+   * @return int
+   *   An integer status code. @see Migration::MESSAGE_*
+   */
+  public function getLevel() {
+    return $this->level;
+  }
+
+  /**
+   * Gets the status of the current item.
+   *
+   * @return int
+   *   An integer status code. @see MigrateMap::STATUS_*
+   */
+  public function getStatus() {
+    return $this->status;
+  }
+
+}

core/modules/migrate/src/MigrateExecutable.php

@@ -0,0 +1,627 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateExecutable.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\Core\Utility\Error;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Exception\RequirementsException;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+
+/**
+ * Defines a migrate executable class.
+ */
+class MigrateExecutable implements MigrateExecutableInterface {
+  use StringTranslationTrait;
+
+  /**
+   * The configuration of the migration to do.
+   *
+   * @var \Drupal\migrate\Entity\Migration
+   */
+  protected $migration;
+
+  /**
+   * The number of successfully imported rows since feedback was given.
+   *
+   * @var int
+   */
+  protected $successesSinceFeedback;
+
+  /**
+   * The number of rows that were successfully processed.
+   *
+   * @var int
+   */
+  protected $totalSuccesses;
+
+  /**
+   * Status of one row.
+   *
+   * The value is a MigrateIdMapInterface::STATUS_* constant, for example:
+   * STATUS_IMPORTED.
+   *
+   * @var int
+   */
+  protected $sourceRowStatus;
+
+  /**
+   * The number of rows processed.
+   *
+   * The total attempted, whether or not they were successful.
+   *
+   * @var int
+   */
+  protected $totalProcessed;
+
+  /**
+   * The queued messages not yet saved.
+   *
+   * Each element in the array is an array with two keys:
+   * - 'message': The message string.
+   * - 'level': The level, a MigrationInterface::MESSAGE_* constant.
+   *
+   * @var array
+   */
+  protected $queuedMessages = array();
+
+  /**
+   * The options that can be set when executing the migration.
+   *
+   * Values can be set for:
+   * - 'limit': Sets a time limit.
+   *
+   * @var array
+   */
+  protected $options;
+
+  /**
+   * The PHP max_execution_time.
+   *
+   * @var int
+   */
+  protected $maxExecTime;
+
+  /**
+   * The ratio of the memory limit at which an operation will be interrupted.
+   *
+   * @var float
+   */
+  protected $memoryThreshold = 0.85;
+
+  /**
+   * The ratio of the time limit at which an operation will be interrupted.
+   *
+   * @var float
+   */
+  public $timeThreshold = 0.90;
+
+  /**
+   * The time limit when executing the migration.
+   *
+   * @var array
+   */
+  public $limit = array();
+
+  /**
+   * The configuration values of the source.
+   *
+   * @var array
+   */
+  protected $sourceIdValues;
+
+  /**
+   * The number of rows processed since feedback was given.
+   *
+   * @var int
+   */
+  protected $processedSinceFeedback = 0;
+
+  /**
+   * The PHP memory_limit expressed in bytes.
+   *
+   * @var int
+   */
+  protected $memoryLimit;
+
+  /**
+   * The rollback action to be saved for the current row.
+   *
+   * @var int
+   */
+  public $rollbackAction;
+
+  /**
+   * An array of counts. Initially used for cache hit/miss tracking.
+   *
+   * @var array
+   */
+  protected $counts = array();
+
+  /**
+   * The maximum number of items to pass in a single call during a rollback.
+   *
+   * For use in bulkRollback(). Can be overridden in derived class constructor.
+   *
+   * @var int
+   */
+  protected $rollbackBatchSize = 50;
+
+  /**
+   * The object currently being constructed.
+   *
+   * @var \stdClass
+   */
+  protected $destinationValues;
+
+  /**
+   * The source.
+   *
+   * @var \Drupal\migrate\Plugin\MigrateSourceInterface
+   */
+  protected $source;
+
+  /**
+   * The current data row retrieved from the source.
+   *
+   * @var \stdClass
+   */
+  protected $sourceValues;
+
+  /**
+   * Constructs a MigrateExecutable and verifies and sets the memory limit.
+   *
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   The migration to run.
+   * @param \Drupal\migrate\MigrateMessageInterface $message
+   *   The message to record.
+   *
+   * @throws \Drupal\migrate\MigrateException
+   */
+  public function __construct(MigrationInterface $migration, MigrateMessageInterface $message) {
+    $this->migration = $migration;
+    $this->message = $message;
+    $this->migration->getIdMap()->setMessage($message);
+    // Record the memory limit in bytes
+    $limit = trim(ini_get('memory_limit'));
+    if ($limit == '-1') {
+      $this->memoryLimit = PHP_INT_MAX;
+    }
+    else {
+      if (!is_numeric($limit)) {
+        $last = strtolower(substr($limit, -1));
+        switch ($last) {
+          case 'g':
+            $limit *= 1024;
+          case 'm':
+            $limit *= 1024;
+          case 'k':
+            $limit *= 1024;
+            break;
+          default:
+            throw new MigrateException($this->t('Invalid PHP memory_limit !limit',
+              array('!limit' => $limit)));
+        }
+      }
+      $this->memoryLimit = $limit;
+    }
+    // Record the maximum execution time limit.
+    $this->maxExecTime = ini_get('max_execution_time');
+  }
+
+  /**
+   * Returns the source.
+   *
+   * Makes sure source is initialized based on migration settings.
+   *
+   * @return \Drupal\migrate\Plugin\MigrateSourceInterface
+   *   The source.
+   */
+  protected function getSource() {
+    if (!isset($this->source)) {
+      $this->source = $this->migration->getSourcePlugin();
+
+      // @TODO, find out how to remove this.
+      // @see https://www.drupal.org/node/2443617
+      $this->source->migrateExecutable = $this;
+    }
+    return $this->source;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import() {
+    // Knock off migration if the requirements haven't been met.
+    try {
+      $this->migration->checkRequirements();
+    }
+    catch (RequirementsException $e) {
+      $this->message->display(
+        $this->t('Migration @id did not meet the requirements. @message @requirements', array(
+          '@id' => $this->migration->id(),
+          '@message' => $e->getMessage(),
+          '@requirements' => $e->getRequirementsString(),
+        )), 'error');
+      return MigrationInterface::RESULT_FAILED;
+    }
+
+    $return = MigrationInterface::RESULT_COMPLETED;
+    $source = $this->getSource();
+    $id_map = $this->migration->getIdMap();
+
+    try {
+      $source->rewind();
+    }
+    catch (\Exception $e) {
+      $this->message->display(
+        $this->t('Migration failed with source plugin exception: !e', array('!e' => $e->getMessage())), 'error');
+      return MigrationInterface::RESULT_FAILED;
+    }
+
+    $destination = $this->migration->getDestinationPlugin();
+    while ($source->valid()) {
+      $row = $source->current();
+      if ($this->sourceIdValues = $row->getSourceIdValues()) {
+        // Wipe old messages, and save any new messages.
+        $id_map->delete($this->sourceIdValues, TRUE);
+        $this->saveQueuedMessages();
+      }
+
+      try {
+        $this->processRow($row);
+        $save = TRUE;
+      }
+      catch (MigrateSkipRowException $e) {
+        $id_map->saveIdMapping($row, array(), MigrateIdMapInterface::STATUS_IGNORED, $this->rollbackAction);
+        $save = FALSE;
+      }
+
+      if ($save) {
+        try {
+          $destination_id_values = $destination->import($row, $id_map->lookupDestinationId($this->sourceIdValues));
+          if ($destination_id_values) {
+            // We do not save an idMap entry for config.
+            if ($destination_id_values !== TRUE) {
+              $id_map->saveIdMapping($row, $destination_id_values, $this->sourceRowStatus, $this->rollbackAction);
+            }
+            $this->successesSinceFeedback++;
+            $this->totalSuccesses++;
+          }
+          else {
+            $id_map->saveIdMapping($row, array(), MigrateIdMapInterface::STATUS_FAILED, $this->rollbackAction);
+            if (!$id_map->messageCount()) {
+              $message = $this->t('New object was not saved, no error provided');
+              $this->saveMessage($message);
+              $this->message->display($message);
+            }
+          }
+        }
+        catch (MigrateException $e) {
+          $this->migration->getIdMap()->saveIdMapping($row, array(), $e->getStatus(), $this->rollbackAction);
+          $this->saveMessage($e->getMessage(), $e->getLevel());
+          $this->message->display($e->getMessage(), 'error');
+        }
+        catch (\Exception $e) {
+          $this->migration->getIdMap()->saveIdMapping($row, array(), MigrateIdMapInterface::STATUS_FAILED, $this->rollbackAction);
+          $this->handleException($e);
+        }
+      }
+      $this->totalProcessed++;
+      $this->processedSinceFeedback++;
+      if ($high_water_property = $this->migration->get('highWaterProperty')) {
+        $this->migration->saveHighWater($row->getSourceProperty($high_water_property['name']));
+      }
+
+      // Reset row properties.
+      unset($sourceValues, $destinationValues);
+      $this->sourceRowStatus = MigrateIdMapInterface::STATUS_IMPORTED;
+
+      if (($return = $this->checkStatus()) != MigrationInterface::RESULT_COMPLETED) {
+        break;
+      }
+      if ($this->timeOptionExceeded()) {
+        break;
+      }
+      try {
+        $source->next();
+      }
+      catch (\Exception $e) {
+        $this->message->display(
+          $this->t('Migration failed with source plugin exception: !e',
+            array('!e' => $e->getMessage())), 'error');
+        return MigrationInterface::RESULT_FAILED;
+      }
+    }
+
+    /**
+     * @TODO uncomment this
+     */
+    #$this->progressMessage($return);
+
+    $this->migration->setMigrationResult($return);
+    return $return;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processRow(Row $row, array $process = NULL, $value = NULL) {
+    foreach ($this->migration->getProcessPlugins($process) as $destination => $plugins) {
+      $multiple = FALSE;
+      /** @var $plugin \Drupal\migrate\Plugin\MigrateProcessInterface */
+      foreach ($plugins as $plugin) {
+        $definition = $plugin->getPluginDefinition();
+        // Many plugins expect a scalar value but the current value of the
+        // pipeline might be multiple scalars (this is set by the previous
+        // plugin) and in this case the current value needs to be iterated
+        // and each scalar separately transformed.
+        if ($multiple && !$definition['handle_multiples']) {
+          $new_value = array();
+          if (!is_array($value)) {
+            throw new MigrateException(sprintf('Pipeline failed for destination %s: %s got instead of an array,', $destination, $value));
+          }
+          $break = FALSE;
+          foreach ($value as $scalar_value) {
+            try {
+              $new_value[] = $plugin->transform($scalar_value, $this, $row, $destination);
+            }
+            catch (MigrateSkipProcessException $e) {
+              $break = TRUE;
+            }
+          }
+          $value = $new_value;
+          if ($break) {
+            break;
+          }
+        }
+        else {
+          try {
+            $value = $plugin->transform($value, $this, $row, $destination);
+          }
+          catch (MigrateSkipProcessException $e) {
+            break;
+          }
+          $multiple = $multiple || $plugin->multiple();
+        }
+      }
+      // No plugins means do not set.
+      if ($plugins) {
+        $row->setDestinationProperty($destination, $value);
+      }
+      // Reset the value.
+      $value = NULL;
+    }
+  }
+
+  /**
+   * Fetches the key array for the current source record.
+   *
+   * @return array
+   *   The current source IDs.
+   */
+  protected function currentSourceIds() {
+    return $this->getSource()->getCurrentIds();
+  }
+
+  /**
+   * Tests whether we've exceeded the designated time limit.
+   *
+   * @return bool
+   *   TRUE if the threshold is exceeded, FALSE if not.
+   */
+  protected function timeOptionExceeded() {
+    // If there is no time limit, then it is not exceeded.
+    if (!$time_limit = $this->getTimeLimit()) {
+      return FALSE;
+    }
+    // Calculate if the time limit is exceeded.
+    $time_elapsed = $this->getTimeElapsed();
+    if ($time_elapsed >= $time_limit) {
+      return TRUE;
+    }
+    else {
+      return FALSE;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getTimeLimit() {
+    $limit = $this->limit;
+    if (isset($limit['unit']) && isset($limit['value']) && ($limit['unit'] == 'seconds' || $limit['unit'] == 'second')) {
+      return $limit['value'];
+    }
+    else {
+      return NULL;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function saveMessage($message, $level = MigrationInterface::MESSAGE_ERROR) {
+    $this->migration->getIdMap()->saveMessage($this->sourceIdValues, $message, $level);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function queueMessage($message, $level = MigrationInterface::MESSAGE_ERROR) {
+    $this->queuedMessages[] = array('message' => $message, 'level' => $level);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function saveQueuedMessages() {
+    foreach ($this->queuedMessages as $queued_message) {
+      $this->saveMessage($queued_message['message'], $queued_message['level']);
+    }
+    $this->queuedMessages = array();
+  }
+
+  /**
+   * Checks for exceptional conditions, and display feedback.
+   *
+   * Standard top-of-loop stuff, common between rollback and import.
+   */
+  protected function checkStatus() {
+    if ($this->memoryExceeded()) {
+      return MigrationInterface::RESULT_INCOMPLETE;
+    }
+    if ($this->maxExecTimeExceeded()) {
+      return MigrationInterface::RESULT_INCOMPLETE;
+    }
+    /*
+     * @TODO uncomment this
+    if ($this->getStatus() == MigrationInterface::STATUS_STOPPING) {
+      return MigrationBase::RESULT_STOPPED;
+    }
+    */
+    // If feedback is requested, produce a progress message at the proper time
+    /*
+     * @TODO uncomment this
+    if (isset($this->feedback)) {
+      if (($this->feedback_unit == 'seconds' && time() - $this->lastfeedback >= $this->feedback) ||
+          ($this->feedback_unit == 'items' && $this->processed_since_feedback >= $this->feedback)) {
+        $this->progressMessage(MigrationInterface::RESULT_INCOMPLETE);
+      }
+    }
+    */
+
+    return MigrationInterface::RESULT_COMPLETED;
+  }
+
+  /**
+   * Tests whether we've exceeded the desired memory threshold.
+   *
+   * If so, output a message.
+   *
+   * @return bool
+   *   TRUE if the threshold is exceeded, otherwise FALSE.
+   */
+  protected function memoryExceeded() {
+    $usage = $this->getMemoryUsage();
+    $pct_memory = $usage / $this->memoryLimit;
+    if (!$threshold = $this->memoryThreshold) {
+      return FALSE;
+    }
+    if ($pct_memory > $threshold) {
+      $this->message->display(
+        $this->t('Memory usage is !usage (!pct% of limit !limit), reclaiming memory.',
+          array('!pct' => round($pct_memory*100),
+                '!usage' => $this->formatSize($usage),
+                '!limit' => $this->formatSize($this->memoryLimit))),
+        'warning');
+      $usage = $this->attemptMemoryReclaim();
+      $pct_memory = $usage / $this->memoryLimit;
+      // Use a lower threshold - we don't want to be in a situation where we keep
+      // coming back here and trimming a tiny amount
+      if ($pct_memory > (0.90 * $threshold)) {
+        $this->message->display(
+          $this->t('Memory usage is now !usage (!pct% of limit !limit), not enough reclaimed, starting new batch',
+            array('!pct' => round($pct_memory*100),
+                  '!usage' => $this->formatSize($usage),
+                  '!limit' => $this->formatSize($this->memoryLimit))),
+          'warning');
+        return TRUE;
+      }
+      else {
+        $this->message->display(
+          $this->t('Memory usage is now !usage (!pct% of limit !limit), reclaimed enough, continuing',
+            array('!pct' => round($pct_memory*100),
+                  '!usage' => $this->formatSize($usage),
+                  '!limit' => $this->formatSize($this->memoryLimit))),
+          'warning');
+        return FALSE;
+      }
+    }
+    else {
+      return FALSE;
+    }
+  }
+
+  /**
+   * Returns the memory usage so far.
+   *
+   * @return int
+   *   The memory usage.
+   */
+  protected function getMemoryUsage() {
+    return memory_get_usage();
+  }
+
+  /**
+   * Tries to reclaim memory.
+   *
+   * @return int
+   *   The memory usage after reclaim.
+   */
+  protected function attemptMemoryReclaim() {
+    // First, try resetting Drupal's static storage - this frequently releases
+    // plenty of memory to continue.
+    drupal_static_reset();
+    // @TODO: explore resetting the container.
+    return memory_get_usage();
+  }
+
+  /**
+   * Generates a string representation for the given byte count.
+   *
+   * @param int $size
+   *   A size in bytes.
+   *
+   * @return string
+   *   A translated string representation of the size.
+   */
+  protected function formatSize($size) {
+    return format_size($size);
+  }
+
+  /**
+   * Tests whether we're approaching the PHP maximum execution time limit.
+   *
+   * @return bool
+   *   TRUE if the threshold is exceeded, FALSE if not.
+   */
+  protected function maxExecTimeExceeded() {
+    return $this->maxExecTime && (($this->getTimeElapsed() / $this->maxExecTime) > $this->timeThreshold);
+  }
+
+  /**
+   * Returns the time elapsed.
+   *
+   * This allows a test to set a fake elapsed time.
+   */
+  protected function getTimeElapsed() {
+    return time() - REQUEST_TIME;
+  }
+
+  /**
+   * Takes an Exception object and both saves and displays it.
+   *
+   * Pulls in additional information on the location triggering the exception.
+   *
+   * @param \Exception $exception
+   *   Object representing the exception.
+   * @param bool $save
+   *   (optional) Whether to save the message in the migration's mapping table.
+   *   Set to FALSE in contexts where this doesn't make sense.
+   */
+  protected function handleException(\Exception $exception, $save = TRUE) {
+    $result = Error::decodeException($exception);
+    $message = $result['!message'] . ' (' . $result['%file'] . ':' . $result['%line'] . ')';
+    if ($save) {
+      $this->saveMessage($message);
+    }
+    $this->message->display($message, 'error');
+  }
+
+}

core/modules/migrate/src/MigrateExecutableInterface.php

@@ -0,0 +1,71 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateExecutableInterface.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\migrate\Entity\MigrationInterface;
+
+interface MigrateExecutableInterface {
+
+  /**
+   * Performs an import operation - migrate items from source to destination.
+   */
+  public function import();
+
+  /**
+   * Processes a row.
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The $row to be processed.
+   * @param array $process
+   *   (optional) A process pipeline configuration. If not set, the top level
+   *   process configuration in the migration entity is used.
+   * @param mixed $value
+   *   (optional) Initial value of the pipeline for the first destination.
+   *   Usually setting this is not necessary as $process typically starts with
+   *   a 'get'. This is useful only when the $process contains a single
+   *   destination and needs to access a value outside of the source. See
+   *   \Drupal\migrate\Plugin\migrate\process\Iterator::transformKey for an
+   *   example.
+   *
+   * @throws \Drupal\migrate\MigrateException
+   */
+  public function processRow(Row $row, array $process = NULL, $value = NULL);
+
+  /**
+   * Returns the time limit.
+   *
+   * @return null|int
+   *   The time limit, NULL if no limit or if the units were not in seconds.
+   */
+  public function getTimeLimit();
+
+  /**
+   * Passes messages through to the map class.
+   *
+   * @param string $message
+   *   The message to record.
+   * @param int $level
+   *   (optional) Message severity (defaults to MESSAGE_ERROR).
+   */
+  public function saveMessage($message, $level = MigrationInterface::MESSAGE_ERROR);
+
+  /**
+   * Queues messages to be later saved through the map class.
+   *
+   * @param string $message
+   *   The message to record.
+   * @param int $level
+   *   (optional) Message severity (defaults to MESSAGE_ERROR).
+   */
+  public function queueMessage($message, $level = MigrationInterface::MESSAGE_ERROR);
+
+  /**
+   * Saves any messages we've queued up to the message table.
+   */
+  public function saveQueuedMessages();
+}

core/modules/migrate/src/MigrateMessage.php

@@ -0,0 +1,35 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateMessage.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\Core\Logger\RfcLogLevel;
+
+/**
+ * Defines a migrate message class.
+ */
+class MigrateMessage implements MigrateMessageInterface {
+
+  /**
+   * The map between migrate status and watchdog severity.
+   *
+   * @var array
+   */
+  protected $map = array(
+    'status' => RfcLogLevel::INFO,
+    'error' => RfcLogLevel::ERROR,
+  );
+
+  /**
+   * {@inheritdoc}
+   */
+  public function display($message, $type = 'status') {
+    $type = isset($this->map[$type]) ? $this->map[$type] : RfcLogLevel::NOTICE;
+    \Drupal::logger('migrate')->log($type, $message);
+  }
+
+}

core/modules/migrate/src/MigrateMessageInterface.php

@@ -0,0 +1,21 @@
+<?php
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateMessageInterface.
+ */
+
+namespace Drupal\migrate;
+
+
+interface MigrateMessageInterface {
+
+  /**
+   * Displays a migrate message.
+   *
+   * @param string $message
+   *   The message to display.
+   * @param string $type
+   *   The type of message, for example: status or warning.
+   */
+  public function display($message, $type = 'status');
+}

core/modules/migrate/src/MigratePassword.php

@@ -0,0 +1,84 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigratePassword.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\Core\Password\PasswordInterface;
+
+/**
+ * Replaces the original 'password' service in order to prefix the MD5 re-hashed
+ * passwords with the 'U' flag. The new salted hash is recreated on first login
+ * similarly to the D6->D7 upgrade path.
+ */
+class MigratePassword implements PasswordInterface {
+
+  /**
+   * The original password service.
+   *
+   * @var \Drupal\Core\Password\PasswordInterface
+   */
+  protected $originalPassword;
+
+  /**
+   * Indicates if MD5 password prefixing is enabled.
+   */
+  protected $enabled = FALSE;
+
+  /**
+   * Builds the replacement password service class.
+   *
+   * @param \Drupal\Core\Password\PasswordInterface $original_password
+   *   The password object.
+   */
+  public function __construct(PasswordInterface $original_password) {
+    $this->originalPassword = $original_password;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check($password, $hash) {
+    return $this->originalPassword->check($password, $hash);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function needsRehash($hash) {
+    return $this->originalPassword->needsRehash($hash);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function hash($password) {
+    $hash = $this->originalPassword->hash($password);
+
+    // Allow prefixing only if the service was asked to prefix. Check also if
+    // the $password pattern is conforming to a MD5 result.
+    if ($this->enabled && preg_match('/^[0-9a-f]{32}$/', $password)) {
+      $hash = 'U' . $hash;
+    }
+
+    return $hash;
+  }
+
+  /**
+   * Enables the MD5 password prefixing.
+   */
+  public function enableMd5Prefixing() {
+    $this->enabled = TRUE;
+  }
+
+  /**
+   * Disables the MD5 password prefixing.
+   */
+  public function disableMd5Prefixing() {
+    $this->enabled = FALSE;
+  }
+
+}

core/modules/migrate/src/MigrateServiceProvider.php

@@ -0,0 +1,30 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateServiceProvider.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\Core\DependencyInjection\ServiceModifierInterface;
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+
+/**
+ * Swaps the original 'password' service in order to handle password hashing for
+ * user migrations that have passwords hashed to MD5.
+ *
+ * @see \Drupal\migrate\MigratePassword
+ * @see \Drupal\Core\Password\PhpassHashedPassword
+ */
+class MigrateServiceProvider implements ServiceModifierInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function alter(ContainerBuilder $container) {
+    $container->setDefinition('password_original', $container->getDefinition('password'));
+    $container->setDefinition('password', $container->getDefinition('password_migrate'));
+  }
+
+}

core/modules/migrate/src/MigrateSkipProcessException.php

@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateSkipProcessException.
+ */
+
+namespace Drupal\migrate;
+
+/**
+ * This exception is thrown when the rest of the process should be skipped.
+ */
+class MigrateSkipProcessException extends \Exception {
+
+}

core/modules/migrate/src/MigrateSkipRowException.php

@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrateSkipRowException.
+ */
+
+namespace Drupal\migrate;
+
+/**
+ * This exception is thrown when a row should be skipped.
+ */
+class MigrateSkipRowException extends \Exception {
+
+}

core/modules/migrate/src/MigrationStorage.php

@@ -0,0 +1,93 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\MigrationStorage.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\Component\Graph\Graph;
+use Drupal\Core\Config\Entity\ConfigEntityStorage;
+
+/**
+ * Storage for migration entities.
+ */
+class MigrationStorage extends ConfigEntityStorage implements MigrateBuildDependencyInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildDependencyMigration(array $migrations, array $dynamic_ids) {
+    // Migration dependencies defined in the migration storage can be
+    // optional or required. If an optional dependency does not run, the current
+    // migration is still OK to go. Both optional and required dependencies
+    // (if run at all) must run before the current migration.
+    $dependency_graph = array();
+    $requirement_graph = array();
+    $different = FALSE;
+    foreach ($migrations as $migration) {
+      /** @var \Drupal\migrate\Entity\MigrationInterface $migration */
+      $id = $migration->id();
+      $requirements[$id] = array();
+      $dependency_graph[$id]['edges'] = array();
+      $migration_dependencies = $migration->getMigrationDependencies();
+
+      if (isset($migration_dependencies['required'])) {
+        foreach ($migration_dependencies['required'] as $dependency) {
+          if (!isset($dynamic_ids[$dependency])) {
+            $this->addDependency($requirement_graph, $id, $dependency, $dynamic_ids);
+          }
+          $this->addDependency($dependency_graph, $id, $dependency, $dynamic_ids);
+        }
+      }
+      if (isset($migration_dependencies['optional'])) {
+        foreach ($migration_dependencies['optional'] as $dependency) {
+          $different = TRUE;
+          $this->addDependency($dependency_graph, $id, $dependency, $dynamic_ids);
+        }
+      }
+    }
+    $graph_object = new Graph($dependency_graph);
+    $dependency_graph = $graph_object->searchAndSort();
+    if ($different) {
+      $graph_object = new Graph($requirement_graph);
+      $requirement_graph = $graph_object->searchAndSort();
+    }
+    else {
+      $requirement_graph = $dependency_graph;
+    }
+    $weights = array();
+    foreach ($migrations as $migration_id => $migration) {
+      // Populate a weights array to use with array_multisort later.
+      $weights[] = $dependency_graph[$migration_id]['weight'];
+      if (!empty($requirement_graph[$migration_id]['paths'])) {
+        $migration->set('requirements', $requirement_graph[$migration_id]['paths']);
+      }
+    }
+    array_multisort($weights, SORT_DESC, SORT_NUMERIC, $migrations);
+
+    return $migrations;
+  }
+
+  /**
+   * Add one or more dependencies to a graph.
+   *
+   * @param array $graph
+   *   The graph so far.
+   * @param int $id
+   *   The migration id.
+   * @param string $dependency
+   *   The dependency string.
+   * @param array $dynamic_ids
+   *   The dynamic id mapping.
+   */
+  protected function addDependency(array &$graph, $id, $dependency, $dynamic_ids) {
+    $dependencies = isset($dynamic_ids[$dependency]) ? $dynamic_ids[$dependency] : array($dependency);
+    if (!isset($graph[$id]['edges'])) {
+      $graph[$id]['edges'] = array();
+    }
+    $graph[$id]['edges'] += array_combine($dependencies, $dependencies);
+  }
+
+}

core/modules/migrate/src/Plugin/Derivative/MigrateEntity.php

@@ -0,0 +1,77 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\Derivative\MigrateEntity.
+ */
+
+namespace Drupal\migrate\Plugin\Derivative;
+
+use Drupal\Core\Plugin\Discovery\ContainerDeriverInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+class MigrateEntity implements ContainerDeriverInterface {
+
+  /**
+   * List of derivative definitions.
+   *
+   * @var array
+   */
+  protected $derivatives = array();
+
+  /**
+   * The entity definitions
+   *
+   * @var \Drupal\Core\Entity\EntityTypeInterface[]
+   */
+  protected $entityDefinitions;
+
+  /**
+   * Constructs a MigrateEntity object.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeInterface[] $entity_definitions
+   *   A list of entity definition objects.
+   */
+  public function __construct(array $entity_definitions) {
+    $this->entityDefinitions = $entity_definitions;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, $base_plugin_id) {
+    return new static(
+      $container->get('entity.manager')->getDefinitions()
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDerivativeDefinition($derivative_id, $base_plugin_definition) {
+    if (!empty($this->derivatives) && !empty($this->derivatives[$derivative_id])) {
+      return $this->derivatives[$derivative_id];
+    }
+    $this->getDerivativeDefinitions($base_plugin_definition);
+    return $this->derivatives[$derivative_id];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDerivativeDefinitions($base_plugin_definition) {
+    foreach ($this->entityDefinitions as $entity_type => $entity_info) {
+      $class = is_subclass_of($entity_info->getClass(), 'Drupal\Core\Config\Entity\ConfigEntityInterface') ?
+        'Drupal\migrate\Plugin\migrate\destination\EntityConfigBase' :
+        'Drupal\migrate\Plugin\migrate\destination\EntityContentBase';
+      $this->derivatives[$entity_type] = array(
+        'id' => "entity:$entity_type",
+        'class' => $class,
+        'requirements_met' => 1,
+        'provider' => $entity_info->getProvider(),
+      );
+    }
+    return $this->derivatives;
+  }
+
+}

core/modules/migrate/src/Plugin/Derivative/MigrateEntityRevision.php

@@ -0,0 +1,76 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\Derivative\MigrateEntityRevision.
+ */
+
+namespace Drupal\migrate\Plugin\Derivative;
+
+use Drupal\Core\Plugin\Discovery\ContainerDeriverInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+class MigrateEntityRevision implements ContainerDeriverInterface {
+
+  /**
+   * List of derivative definitions.
+   *
+   * @var array
+   */
+  protected $derivatives = array();
+
+  /**
+   * The entity definitions
+   *
+   * @var \Drupal\Core\Entity\EntityTypeInterface[]
+   */
+  protected $entityDefinitions;
+
+  /**
+   * Constructs a MigrateEntity object.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeInterface[] $entity_definitions
+   *   A list of entity definition objects.
+   */
+  public function __construct(array $entity_definitions) {
+    $this->entityDefinitions = $entity_definitions;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, $base_plugin_id) {
+    return new static(
+      $container->get('entity.manager')->getDefinitions()
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDerivativeDefinition($derivative_id, $base_plugin_definition) {
+    if (!empty($this->derivatives) && !empty($this->derivatives[$derivative_id])) {
+      return $this->derivatives[$derivative_id];
+    }
+    $this->getDerivativeDefinitions($base_plugin_definition);
+    return $this->derivatives[$derivative_id];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDerivativeDefinitions($base_plugin_definition) {
+    foreach ($this->entityDefinitions as $entity_type => $entity_info) {
+      if ($entity_info->getKey('revision')) {
+        $this->derivatives[$entity_type] = array(
+          'id' => "entity_revision:$entity_type",
+          'class' => 'Drupal\migrate\Plugin\migrate\destination\EntityRevision',
+          'requirements_met' => 1,
+          'provider' => $entity_info->getProvider(),
+        );
+      }
+    }
+    return $this->derivatives;
+  }
+
+}

core/modules/migrate/src/Plugin/MigrateDestinationInterface.php

@@ -0,0 +1,109 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\MigrateDestinationInterface.
+ */
+
+namespace Drupal\migrate\Plugin;
+
+use Drupal\Component\Plugin\PluginInspectionInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Row;
+
+/**
+ * Destinations are responsible for persisting source data into the destination
+ * Drupal.
+ *
+ * @see \Drupal\migrate\Plugin\destination\DestinationBase
+ * @see \Drupal\migrate\Plugin\MigrateDestinationPluginManager
+ * @see \Drupal\migrate\Annotation\MigrateDestination
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+interface MigrateDestinationInterface extends PluginInspectionInterface {
+
+  /**
+   * Get the destination ids.
+   *
+   * To support MigrateIdMap maps, derived destination classes should return
+   * schema field definition(s) corresponding to the primary key of the
+   * destination being implemented. These are used to construct the destination
+   * key fields of the map table for a migration using this destination.
+   *
+   * @return array
+   *   An array of ids.
+   */
+  public function getIds();
+
+  /**
+   * Returns an array of destination fields.
+   *
+   * Derived classes must implement fields(), returning a list of available
+   * destination fields.
+   *
+   * @todo Review the cases where we need the Migration parameter,
+   * can we avoid that?
+   *
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   (optional) the migration containing this destination.
+   *
+   * @return array
+   *   - Keys: machine names of the fields
+   *   - Values: Human-friendly descriptions of the fields.
+   */
+  public function fields(MigrationInterface $migration = NULL);
+
+
+  /**
+   * Allows pre-processing of an import.
+   *
+   * Derived classes may implement preImport() to do any processing they need
+   * done before over all source rows.
+   */
+  public function preImport();
+
+  /**
+   * Allows pre-processing of a rollback.
+   */
+  public function preRollback();
+
+  /**
+   * Allows post-processing of an import.
+   *
+   * Derived classes may implement postImport(), to do any processing they need
+   * done after looping over all source rows.
+   */
+  public function postImport();
+
+  /**
+   * Allows post-processing of a rollback.
+   */
+  public function postRollback();
+
+  /**
+   * Import the row.
+   *
+   * Derived classes must implement import(), to construct one new object
+   * (pre-populated) using ID mappings in the Migration).
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The row object.
+   * @param array $old_destination_id_values
+   *   The old destination ids.
+   *
+   * @return mixed
+   *   The entity id or an indication of success.
+   */
+  public function import(Row $row, array $old_destination_id_values = array());
+
+  /**
+   * Delete the specified IDs from the target Drupal.
+   *
+   * @param array $destination_identifiers
+   *   The destination ids to delete.
+   */
+  public function rollbackMultiple(array $destination_identifiers);
+
+}

core/modules/migrate/src/Plugin/MigrateDestinationPluginManager.php

@@ -0,0 +1,62 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\MigrateDestinationPluginManager.
+ */
+
+
+namespace Drupal\migrate\Plugin;
+
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+
+/**
+ * Plugin manager for migrate destination plugins.
+ *
+ * @see \Drupal\migrate\Plugin\MigrateDestinationInterface
+ * @see \Drupal\migrate\Plugin\destination\DestinationBase
+ * @see \Drupal\migrate\Annotation\MigrateDestination
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+class MigrateDestinationPluginManager extends MigratePluginManager {
+
+  /**
+   * The theme handler
+   *
+   * @var \Drupal\Core\Extension\ThemeHandlerInterface
+   */
+  protected $themeHandler;
+
+  /**
+   * An associative array where the keys are the enabled modules and themes.
+   *
+   * @var array
+   */
+  protected $providers;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct($type, \Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, EntityManagerInterface $entity_manager, $annotation = 'Drupal\migrate\Annotation\MigrateDestination') {
+    parent::__construct($type, $namespaces, $cache_backend, $module_handler, $annotation);
+    $this->entityManager = $entity_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * A specific createInstance method is necessary to pass the migration on.
+   */
+  public function createInstance($plugin_id, array $configuration = array(), MigrationInterface $migration = NULL) {
+    if (substr($plugin_id, 0, 7) == 'entity:' && !$this->entityManager->getDefinition(substr($plugin_id, 7), FALSE)) {
+      $plugin_id = 'null';
+    }
+    return parent::createInstance($plugin_id, $configuration, $migration);
+  }
+
+}

core/modules/migrate/src/Plugin/MigrateIdMapInterface.php

@@ -0,0 +1,242 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\MigrateIdMapInterface.
+ */
+
+namespace Drupal\migrate\Plugin;
+
+use Drupal\Component\Plugin\PluginInspectionInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateMessageInterface;
+use Drupal\migrate\Row;
+
+/**
+ * Defines an interface for migrate ID mappings.
+ *
+ * Migrate ID mappings maintain a relation between source ID and destination ID
+ * for audit and rollback purposes.
+ */
+interface MigrateIdMapInterface extends \Iterator, PluginInspectionInterface {
+
+  /**
+   * Codes reflecting the current status of a map row.
+   */
+  const STATUS_IMPORTED = 0;
+  const STATUS_NEEDS_UPDATE = 1;
+  const STATUS_IGNORED = 2;
+  const STATUS_FAILED = 3;
+
+  /**
+   * Codes reflecting how to handle the destination item on rollback.
+   */
+  const ROLLBACK_DELETE = 0;
+  const ROLLBACK_PRESERVE = 1;
+
+  /**
+   * Saves a mapping from the source identifiers to the destination identifiers.
+   *
+   * Called upon import of one row, we record a mapping from the source ID
+   * to the destination ID. Also may be called, setting the third parameter to
+   * NEEDS_UPDATE, to signal an existing record should be re-migrated.
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The raw source data. We use the ID map derived from the source object
+   *   to get the source identifier values.
+   * @param array $destination_id_values
+   *   An array of destination identifier values.
+   * @param int $status
+   *   Status of the source row in the map.
+   * @param int $rollback_action
+   *   How to handle the destination object on rollback.
+   */
+  public function saveIdMapping(Row $row, array $destination_id_values, $status = self::STATUS_IMPORTED, $rollback_action = self::ROLLBACK_DELETE);
+
+  /**
+   * Saves a message related to a source record in the migration message table.
+   *
+   * @param array $source_id_values
+   *   The source identifier values of the record in error.
+   * @param string $message
+   *   The message to record.
+   * @param int $level
+   *   Optional message severity (defaults to MESSAGE_ERROR).
+   */
+  public function saveMessage(array $source_id_values, $message, $level = MigrationInterface::MESSAGE_ERROR);
+
+  /**
+   * Prepares to run a full update.
+   *
+   * Prepares this migration to run as an update - that is, in addition to
+   * unmigrated content (source records not in the map table) being imported,
+   * previously-migrated content will also be updated in place by marking all
+   * previously-imported content as ready to be re-imported.
+   */
+  public function prepareUpdate();
+
+  /**
+   * Returns the number of processed items in the map.
+   *
+   * @return int
+   *   The count of records in the map table.
+   */
+  public function processedCount();
+
+  /**
+   * Returns the number of imported items in the map.
+   *
+   * @return int
+   *   The number of imported items.
+   */
+  public function importedCount();
+
+
+  /**
+   * Returns a count of items which are marked as needing update.
+   *
+   * @return int
+   *   The number of items which need updating.
+   */
+  public function updateCount();
+
+  /**
+   * Returns the number of items that failed to import.
+   *
+   * @return int
+   *   The number of items that errored out.
+   */
+  public function errorCount();
+
+  /**
+   * Returns the number of messages saved.
+   *
+   * @return int
+   *   The number of messages.
+   */
+  public function messageCount();
+
+  /**
+   * Deletes the map and message entries for a given source record.
+   *
+   * @param array $source_id_values
+   *   The source identifier values of the record to delete.
+   * @param bool $messages_only
+   *   TRUE to only delete the migrate messages.
+   */
+  public function delete(array $source_id_values, $messages_only = FALSE);
+
+  /**
+   * Deletes the map and message table entries for a given destination row.
+   *
+   * @param array $destination_id_values
+   *   The destination identifier values we should do the deletes for.
+   */
+  public function deleteDestination(array $destination_id_values);
+
+  /**
+   * Deletes the map and message entries for a set of given source records.
+   *
+   * @param array $source_id_values
+   *   The identifier values of the sources we should do the deletes for. Each
+   *   array member is an array of identifier values for one source row.
+   */
+  public function deleteBulk(array $source_id_values);
+
+  /**
+   * Clears all messages from the map.
+   */
+  public function clearMessages();
+
+  /**
+   * Retrieves a row from the map table based on source identifier values.
+   *
+   * @param array $source_id_values
+   *   The source identifier values of the record to retrieve.
+   *
+   * @return array
+   *   The raw row data as an associative array.
+   */
+  public function getRowBySource(array $source_id_values);
+
+  /**
+   * Retrieves a row by the destination identifiers.
+   *
+   * @param array $destination_id_values
+   *   The destination identifier values of the record to retrieve.
+   *
+   * @return array
+   *   The row(s) of data.
+   */
+  public function getRowByDestination(array $destination_id_values);
+
+  /**
+   * Retrieves an array of map rows marked as needing update.
+   *
+   * @param int $count
+   *   The maximum number of rows to return.
+   *
+   * @return array
+   *   Array of map row objects that need updating.
+   */
+  public function getRowsNeedingUpdate($count);
+
+  /**
+   * Looks up the source identifier.
+   *
+   * Given a (possibly multi-field) destination identifier value, return the
+   * (possibly multi-field) source identifier value mapped to it.
+   *
+   * @param array $destination_id_values
+   *   The destination identifier values of the record.
+   *
+   * @return array
+   *   The source identifier values of the record, or NULL on failure.
+   */
+  public function lookupSourceID(array $destination_id_values);
+
+  /**
+   * Looks up the destination identifier.
+   *
+   * Given a (possibly multi-field) source identifier value, return the
+   * (possibly multi-field) destination identifier value it is mapped to.
+   *
+   * @param array $source_id_values
+   *   The source identifier values of the record.
+   *
+   * @return array
+   *   The destination identifier values of the record, or NULL on failure.
+   */
+  public function lookupDestinationId(array $source_id_values);
+
+  /**
+   * Removes any persistent storage used by this map.
+   *
+   * For example, remove the map and message tables.
+   */
+  public function destroy();
+
+  /**
+   * Gets the qualified map table.
+   *
+   * @todo Remove this as this is SQL only and so doesn't belong to the interface.
+   */
+  public function getQualifiedMapTableName();
+
+  /**
+   * Sets the migrate message.
+   *
+   * @param \Drupal\migrate\MigrateMessageInterface $message
+   *   The message to display.
+   */
+  public function setMessage(MigrateMessageInterface $message);
+
+  /**
+   * Sets a specified record to be updated, if it exists.
+   *
+   * @param array $source_id_values
+   *   The source identifier values of the record.
+   */
+  public function setUpdate(array $source_id_values);
+
+}

core/modules/migrate/src/Plugin/MigratePluginManager.php

@@ -0,0 +1,89 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\MigratePluginManager.
+ */
+
+namespace Drupal\migrate\Plugin;
+
+use Drupal\Component\Plugin\Factory\DefaultFactory;
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\DefaultPluginManager;
+use Drupal\migrate\Entity\MigrationInterface;
+
+/**
+ * Manages migrate plugins.
+ *
+ * @see hook_migrate_info_alter()
+ * @see \Drupal\migrate\Annotation\MigrateSource
+ * @see \Drupal\migrate\Plugin\MigrateSourceInterface
+ * @see \Drupal\migrate\Plugin\migrate\source\SourcePluginBase
+ * @see \Drupal\migrate\Annotation\MigrateProcessPlugin
+ * @see \Drupal\migrate\Plugin\MigrateProcessInterface
+ * @see \Drupal\migrate\Plugin\migrate\process\ProcessPluginBase
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+class MigratePluginManager extends DefaultPluginManager {
+
+  /**
+   * Constructs a MigratePluginManager object.
+   *
+   * @param string $type
+   *   The type of the plugin: row, source, process, destination, entity_field,
+   * id_map.
+   * @param \Traversable $namespaces
+   *   An object that implements \Traversable which contains the root paths
+   *   keyed by the corresponding namespace to look for plugin implementations.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
+   *   Cache backend instance to use.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler to invoke the alter hook with.
+   * @param string $annotation
+   *   The annotation class name.
+   */
+  public function __construct($type, \Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, $annotation = 'Drupal\Component\Annotation\PluginID') {
+    $plugin_interface = isset($plugin_interface_map[$type]) ? $plugin_interface_map[$type] : NULL;
+    parent::__construct("Plugin/migrate/$type", $namespaces, $module_handler, $plugin_interface, $annotation);
+    $this->alterInfo('migrate_' . $type . '_info');
+    $this->setCacheBackend($cache_backend, 'migrate_plugins_' . $type);
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * A specific createInstance method is necessary to pass the migration on.
+   */
+  public function createInstance($plugin_id, array $configuration = array(), MigrationInterface $migration = NULL) {
+    $plugin_definition = $this->getDefinition($plugin_id);
+    $plugin_class = DefaultFactory::getPluginClass($plugin_id, $plugin_definition);
+    // If the plugin provides a factory method, pass the container to it.
+    if (is_subclass_of($plugin_class, 'Drupal\Core\Plugin\ContainerFactoryPluginInterface')) {
+      $plugin = $plugin_class::create(\Drupal::getContainer(), $configuration, $plugin_id, $plugin_definition, $migration);
+    }
+    else {
+      $plugin = new $plugin_class($configuration, $plugin_id, $plugin_definition, $migration);
+    }
+    return $plugin;
+  }
+
+  /**
+   * Helper for the plugin type to interface map.
+   *
+   * @return array
+   *   An array map from plugin type to interface.
+   */
+  protected function getPluginInterfaceMap() {
+    return [
+      'destination' => 'Drupal\migrate\Plugin\MigrateDestinationInterface',
+      'process' => 'Drupal\migrate\Plugin\MigrateProcessInterface',
+      'source' => 'Drupal\migrate\Plugin\MigrateSourceInterface',
+      'id_map' => 'Drupal\migrate\Plugin\MigrateIdMapInterface',
+      'entity_field' => 'Drupal\migrate\Plugin\MigrateEntityDestinationFieldInterface',
+    ];
+  }
+
+}

core/modules/migrate/src/Plugin/MigrateProcessInterface.php

@@ -0,0 +1,62 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\MigrateProcessInterface.
+ */
+
+namespace Drupal\migrate\Plugin;
+
+use Drupal\Component\Plugin\PluginInspectionInterface;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+
+/**
+ * An interface for migrate process plugins.
+ *
+ * A process plugin can use any number of methods instead of (but not in
+ * addition to) transform with the same arguments and then the plugin
+ * configuration needs to provide the name of the method to be called via the
+ * "method" key. See \Drupal\migrate\Plugin\migrate\process\SkipOnEmpty and
+ * migrate.migration.d6_field_instance_widget_settings.yml for examples.
+ *
+ * @see \Drupal\migrate\Plugin\MigratePluginManager
+ * @see \Drupal\migrate\ProcessPluginBase
+ * @see \Drupal\migrate\Annotation\MigrateProcessPlugin
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+interface MigrateProcessInterface extends PluginInspectionInterface {
+
+  /**
+   * Performs the associated process.
+   *
+   * @param mixed $value
+   *   The value to be transformed.
+   * @param \Drupal\migrate\MigrateExecutableInterface $migrate_executable
+   *   The migration in which this process is being executed.
+   * @param \Drupal\migrate\Row $row
+   *   The row from the source to process. Normally, just transforming the
+   *   value is adequate but very rarely you might need to change two columns
+   *   at the same time or something like that.
+   * @param string $destination_property
+   *   The destination property currently worked on. This is only used
+   *   together with the $row above.
+   *
+   * @return string|array
+   *   The newly transformed value.
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property);
+
+  /**
+   * Indicates whether the returned value requires multiple handling.
+   *
+   * @return bool
+   *   TRUE when the returned value contains a list of values to be processed.
+   *   For example, when the 'source' property is a string and the value found
+   *   is an array.
+   */
+  public function multiple();
+
+}

core/modules/migrate/src/Plugin/MigrateSourceInterface.php

@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\MigrateSourceInterface.
+ */
+
+namespace Drupal\migrate\Plugin;
+use Drupal\Component\Plugin\PluginInspectionInterface;
+use Drupal\migrate\Row;
+
+/**
+ * Defines an interface for migrate sources.
+ *
+ * @see \Drupal\migrate\Plugin\MigratePluginManager
+ * @see \Drupal\migrate\Annotation\MigrateSource
+ * @see \Drupal\migrate\Plugin\migrate\source\SourcePluginBase
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+interface MigrateSourceInterface extends \Countable, \Iterator, PluginInspectionInterface {
+
+  /**
+   * Returns available fields on the source.
+   *
+   * @return array
+   *   Available fields in the source, keys are the field machine names as used
+   *   in field mappings, values are descriptions.
+   */
+  public function fields();
+
+  /**
+   * Returns the iterator that will yield the row arrays to be processed.
+   *
+   * @return \Iterator
+   *   The iterator object.
+   *
+   * @throws \Exception
+   *   Cannot obtain a valid iterator.
+   */
+  public function getIterator();
+
+  /**
+   * Add additional data to the row.
+   *
+   * @param \Drupal\Migrate\Row $row
+   *   The row object.
+   *
+   * @return bool
+   *   FALSE if this row needs to be skipped.
+   */
+  public function prepareRow(Row $row);
+
+  public function __toString();
+
+  /**
+   * Get the source ids.
+   *
+   * @return array
+   *   The source ids.
+   */
+  public function getIds();
+
+}

core/modules/migrate/src/Plugin/RequirementsInterface.php

@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\RequirementsInterface.
+ */
+
+namespace Drupal\migrate\Plugin;
+
+/**
+ * An interface to check for a migrate plugin requirements.
+ */
+interface RequirementsInterface {
+
+  /**
+   * Checks if requirements for this plugin are OK.
+   *
+   * @throws \Drupal\migrate\Exception\RequirementsException
+   *   Thrown when requirements are not met.
+   */
+  public function checkRequirements();
+
+}

core/modules/migrate/src/Plugin/SourceEntityInterface.php

@@ -0,0 +1,32 @@
+<?php
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\SourceEntityInterface.
+ */
+
+namespace Drupal\migrate\Plugin;
+
+/**
+ * Interface for sources providing an entity.
+ */
+interface SourceEntityInterface {
+
+  /**
+   * Whether this migration has a bundle migration.
+   *
+   * @return bool
+   *   TRUE when the bundle_migration key is required.
+   */
+  public function bundleMigrationRequired();
+
+  /**
+   * The entity type id (user, node etc).
+   *
+   * This function is used when bundleMigrationRequired() is FALSE.
+   *
+   * @return string
+   *   The entity type id.
+   */
+  public function entityTypeId();
+
+}

core/modules/migrate/src/Plugin/migrate/destination/Book.php

@@ -0,0 +1,35 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\Book.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "book",
+ *   provider = "book"
+ * )
+ */
+class Book extends EntityContentBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static function getEntityTypeId($plugin_id) {
+    return 'node';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function updateEntity(EntityInterface $entity, Row $row) {
+    $entity->book = $row->getDestinationProperty('book');
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/ComponentEntityDisplayBase.php

@@ -0,0 +1,71 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\ComponentEntityDisplayBase.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Row;
+
+abstract class ComponentEntityDisplayBase extends DestinationBase {
+
+  const MODE_NAME = '';
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    $values = array();
+    // array_intersect_key() won't work because the order is important because
+    // this is also the return value.
+    foreach (array_keys($this->getIds()) as $id) {
+      $values[$id] = $row->getDestinationProperty($id);
+    }
+    $entity = $this->getEntity($values['entity_type'], $values['bundle'], $values[static::MODE_NAME]);
+    if (!$row->getDestinationProperty('hidden')) {
+      $entity->setComponent($values['field_name'], $row->getDestinationProperty('options') ?: array());
+    }
+    else {
+      $entity->removeComponent($values['field_name']);
+    }
+    $entity->save();
+    return array_values($values);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['entity_type']['type'] = 'string';
+    $ids['bundle']['type'] = 'string';
+    $ids[static::MODE_NAME]['type'] = 'string';
+    $ids['field_name']['type'] = 'string';
+    return $ids;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields(MigrationInterface $migration = NULL) {
+    // This is intentionally left empty.
+  }
+
+  /**
+   * Get the entity.
+   *
+   * @param string $entity_type
+   *   The entity type to retrieve.
+   * @param string $bundle
+   *   The entity bundle.
+   * @param string $mode
+   *   The display mode.
+   *
+   * @return \Drupal\Core\Entity\Display\EntityDisplayInterface
+   *   The entity display object.
+   */
+  protected abstract function getEntity($entity_type, $bundle, $mode);
+
+}

core/modules/migrate/src/Plugin/migrate/destination/Config.php

@@ -0,0 +1,121 @@
+<?php
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\Config.
+ *
+ * Provides Configuration Management destination plugin.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Component\Plugin\DependentPluginInterface;
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Entity\DependencyTrait;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\Core\Config\Config as ConfigObject;
+
+/**
+ * Persist data to the config system.
+ *
+ * When a property is NULL, the default is used unless the configuration option
+ * 'store null' is set to TRUE.
+ *
+ * @MigrateDestination(
+ *   id = "config"
+ * )
+ */
+class Config extends DestinationBase implements ContainerFactoryPluginInterface, DependentPluginInterface {
+  use DependencyTrait;
+
+  /**
+   * The config object.
+   *
+   * @var \Drupal\Core\Config\Config
+   */
+  protected $config;
+
+  /**
+   * Constructs a Config destination object.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin ID for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   The migration entity.
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The configuration factory.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, ConfigFactoryInterface $config_factory) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
+    $this->config = $config_factory->getEditable($configuration['config_name']);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('config.factory')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    foreach ($row->getRawDestination() as $key => $value) {
+      if (isset($value) || !empty($this->configuration['store null'])) {
+        $this->config->set(str_replace(Row::PROPERTY_SEPARATOR, '.', $key), $value);
+      }
+    }
+    $this->config->save();
+    return TRUE;
+  }
+
+  /**
+   * Throw an exception because config can not be rolled back.
+   *
+   * @param array $destination_keys
+   *   The array of destination ids to roll back.
+   *
+   * @throws \Drupal\migrate\MigrateException
+   */
+  public function rollbackMultiple(array $destination_keys) {
+    throw new MigrateException('Configuration can not be rolled back');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields(MigrationInterface $migration = NULL) {
+    // @todo Dynamically fetch fields using Config Schema API.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    return array();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function calculateDependencies() {
+    $provider = explode('.', $this->config->getName(), 2)[0];
+    $this->addDependency('module', $provider);
+    return $this->dependencies;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/DestinationBase.php

@@ -0,0 +1,118 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\DestinationBase.
+ */
+
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Plugin\PluginBase;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Exception\RequirementsException;
+use Drupal\migrate\Plugin\MigrateDestinationInterface;
+use Drupal\migrate\Plugin\RequirementsInterface;
+
+/**
+ * Base class for migrate destination classes.
+ *
+ * @see \Drupal\migrate\Plugin\MigrateDestinationInterface
+ * @see \Drupal\migrate\Plugin\MigrateDestinationPluginManager
+ * @see \Drupal\migrate\Annotation\MigrateDestination
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+abstract class DestinationBase extends PluginBase implements MigrateDestinationInterface, RequirementsInterface {
+
+  /**
+   * The migration.
+   *
+   * @var \Drupal\migrate\Entity\MigrationInterface
+   */
+  protected $migration;
+
+  /**
+   * Constructs an entity destination plugin.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param MigrationInterface $migration
+   *   The migration.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->migration = $migration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function checkRequirements() {
+    if (empty($this->pluginDefinition['requirements_met'])) {
+      throw new RequirementsException();
+    }
+  }
+
+  /**
+   * Modify the Row before it is imported.
+   */
+  public function preImport() {
+    // By default we do nothing.
+  }
+
+  /**
+   * Modify the Row before it is rolled back.
+   */
+  public function preRollback() {
+    // By default we do nothing.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function postImport() {
+    // By default we do nothing.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function postRollback() {
+    // By default we do nothing.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function rollbackMultiple(array $destination_identifiers) {
+    // By default we do nothing.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCreated() {
+    // TODO: Implement getCreated() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getUpdated() {
+    // TODO: Implement getUpdated() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function resetStats() {
+    // TODO: Implement resetStats() method.
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/Entity.php

@@ -0,0 +1,182 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\Entity.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Component\Plugin\DependentPluginInterface;
+use Drupal\Core\Entity\DependencyTrait;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity",
+ *   deriver = "Drupal\migrate\Plugin\Derivative\MigrateEntity"
+ * )
+ */
+abstract class Entity extends DestinationBase implements ContainerFactoryPluginInterface, DependentPluginInterface {
+  use DependencyTrait;
+
+  /**
+   * The entity storage.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  protected $storage;
+
+  /**
+   * The list of the bundles of this entity type.
+   *
+   * @var array
+   */
+  protected $bundles;
+
+  /**
+   * Construct a new entity.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param MigrationInterface $migration
+   *   The migration.
+   * @param EntityStorageInterface $storage
+   *   The storage for this entity type.
+   * @param array $bundles
+   *   The list of bundles this entity type has.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityStorageInterface $storage, array $bundles) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
+    $this->storage = $storage;
+    $this->bundles = $bundles;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    $entity_type_id = static::getEntityTypeId($plugin_id);
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('entity.manager')->getStorage($entity_type_id),
+      array_keys($container->get('entity.manager')->getBundleInfo($entity_type_id))
+    );
+  }
+
+  /**
+   * Finds the entity type from configuration or plugin id.
+   *
+   * @param string $plugin_id
+   *   The plugin id.
+   *
+   * @return string
+   *   The entity type.
+   */
+  protected static function getEntityTypeId($plugin_id) {
+    // Remove "entity:"
+    return substr($plugin_id, 7);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields(MigrationInterface $migration = NULL) {
+    // TODO: Implement fields() method.
+  }
+
+  /**
+   * Creates or loads an entity.
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The row object.
+   * @param array $old_destination_id_values
+   *   The old destination ids.
+   *
+   * @return \Drupal\Core\Entity\EntityInterface
+   *   The entity we're importing into.
+   */
+  protected function getEntity(Row $row, array $old_destination_id_values) {
+    $entity_id = $old_destination_id_values ? reset($old_destination_id_values) : $this->getEntityId($row);
+    if (!empty($entity_id) && ($entity = $this->storage->load($entity_id))) {
+      $this->updateEntity($entity, $row);
+    }
+    else {
+      $values = $row->getDestination();
+      // Stubs might not have the bundle specified.
+      if ($row->isStub()) {
+        $values = $this->processStubValues($values);
+      }
+      $entity = $this->storage->create($values);
+      $entity->enforceIsNew();
+    }
+    return $entity;
+  }
+
+  /**
+   * Get the entity id of the row.
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The row of data.
+   * @return string
+   *   The entity id for the row we're importing.
+   */
+  protected function getEntityId(Row $row) {
+    return $row->getDestinationProperty($this->getKey('id'));
+  }
+
+  /**
+   * Process the stub values.
+   *
+   * @param array $values
+   *   An array of destination values.
+   *
+   * @return array
+   *   The processed stub values.
+   */
+  protected function processStubValues(array $values) {
+    $values = array_intersect_key($values, $this->getIds());
+
+    $bundle_key = $this->getKey('bundle');
+    if ($bundle_key && !isset($values[$bundle_key])) {
+      $values[$bundle_key] = reset($this->bundles);
+    }
+
+    return $values;
+  }
+
+  /**
+   * Returns a specific entity key.
+   *
+   * @param string $key
+   *   The name of the entity key to return.
+   *
+   * @return string|bool
+   *   The entity key, or FALSE if it does not exist.
+   *
+   * @see \Drupal\Core\Entity\EntityTypeInterface::getKeys()
+   */
+  protected function getKey($key) {
+    return $this->storage->getEntityType()->getKey($key);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function calculateDependencies() {
+    $this->addDependency('module', $this->storage->getEntityType()->getProvider());
+    return $this->dependencies;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityBaseFieldOverride.php

@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityBaseFieldOverride.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:base_field_override"
+ * )
+ */
+class EntityBaseFieldOverride extends EntityConfigBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEntityId(Row $row) {
+    $entity_type = $row->getDestinationProperty('entity_type');
+    $bundle = $row->getDestinationProperty('bundle');
+    $field_name = $row->getDestinationProperty('field_name');
+    return "$entity_type.$bundle.$field_name";
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityComment.php

@@ -0,0 +1,90 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityComment.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\State\StateInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Plugin\MigratePluginManager;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:comment"
+ * )
+ */
+class EntityComment extends EntityContentBase {
+
+  /**
+   * The state storage object.
+   *
+   * @var \Drupal\Core\State\StateInterface
+   */
+  protected $state;
+
+  /**
+   * Builds an comment entity destination.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param MigrationInterface $migration
+   *   The migration.
+   * @param EntityStorageInterface $storage
+   *   The storage for this entity type.
+   * @param array $bundles
+   *   The list of bundles this entity type has.
+   * @param \Drupal\migrate\Plugin\MigratePluginManager $plugin_manager
+   *   The migrate plugin manager.
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   *   The entity manager service.
+   * @param \Drupal\Core\State\StateInterface $state
+   *   The state storage object.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityStorageInterface $storage, array $bundles, EntityManagerInterface $entity_manager, StateInterface $state) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $storage, $bundles, $entity_manager);
+    $this->state = $state;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    $entity_type = static::getEntityTypeId($plugin_id);
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('entity.manager')->getStorage($entity_type),
+      array_keys($container->get('entity.manager')->getBundleInfo($entity_type)),
+      $container->get('entity.manager'),
+      $container->get('state')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    if ($row->isStub() && ($state = $this->state->get('comment.maintain_entity_statistics', 0))) {
+      $this->state->set('comment.maintain_entity_statistics', 0);
+    }
+    $return = parent::import($row, $old_destination_id_values);
+    if ($row->isStub() && $state) {
+      $this->state->set('comment.maintain_entity_statistics', $state);
+    }
+    return $return;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityCommentType.php

@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityCommentType.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:comment_type"
+ * )
+ */
+class EntityCommentType extends EntityConfigBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    $entity_ids = parent::import($row, $old_destination_id_values);
+    \Drupal::service('comment.manager')->addBodyField(reset($entity_ids));
+    return $entity_ids;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityConfigBase.php

@@ -0,0 +1,123 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityConfigBase.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Component\Utility\NestedArray;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\Row;
+
+/**
+ * Class for importing configuration entities.
+ *
+ * This class serves as the import class for most configuration entities.
+ * It can be necessary to provide a specific entity class if the configuration
+ * entity has a compound id (see EntityFieldEntity) or it has specific setter
+ * methods (see EntityDateFormat). When implementing an entity destination for
+ * the latter case, make sure to add a test not only for importing but also
+ * for re-importing (if that is supported).
+ */
+class EntityConfigBase extends Entity {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    if ($row->isStub()) {
+      throw new MigrateException('Config entities can not be stubbed.');
+    }
+    $ids = $this->getIds();
+    $id_key = $this->getKey('id');
+    if (count($ids) > 1) {
+      // Ids is keyed by the key name so grab the keys.
+      $id_keys = array_keys($ids);
+      if (!$row->getDestinationProperty($id_key)) {
+        // Set the id into the destination in for form "val1.val2.val3".
+        $row->setDestinationProperty($id_key, $this->generateId($row, $id_keys));
+      }
+    }
+    $entity = $this->getEntity($row, $old_destination_id_values);
+    $entity->save();
+    if (count($ids) > 1) {
+      // This can only be a config entity, content entities have their id key
+      // and that's it.
+      $return = array();
+      foreach ($id_keys as $id_key) {
+        $return[] = $entity->get($id_key);
+      }
+      return $return;
+    }
+    return array($entity->id());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $id_key = $this->getKey('id');
+    $ids[$id_key]['type'] = 'string';
+    return $ids;
+  }
+
+
+  /**
+   * Updates an entity with the contents of a row.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   The entity to update.
+   * @param \Drupal\migrate\Row $row
+   *   The row object to update from.
+   */
+  protected function updateEntity(EntityInterface $entity, Row $row) {
+    foreach ($row->getRawDestination() as $property => $value) {
+      $this->updateEntityProperty($entity, explode(Row::PROPERTY_SEPARATOR, $property), $value);
+    }
+  }
+
+  /**
+   * Updates a (possible nested) entity property with a value.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   The config entity.
+   * @param array $parents
+   *   The array of parents.
+   * @param string|object $value
+   *   The value to update to.
+   */
+  protected function updateEntityProperty(EntityInterface $entity, array $parents, $value) {
+    $top_key = array_shift($parents);
+    $entity_value = $entity->get($top_key);
+    if (is_array($entity_value)) {
+      NestedArray::setValue($entity_value, $parents, $value);
+    }
+    else {
+      $entity_value = $value;
+    }
+    $entity->set($top_key, $entity_value);
+  }
+
+  /**
+   * Generate an entity id.
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The current row.
+   * @param array $ids
+   *   The destination ids.
+   *
+   * @return string
+   *   The generated entity id.
+   */
+  protected function generateId(Row $row, array $ids) {
+    $id_values = array();
+    foreach ($ids as $id) {
+      $id_values[] = $row->getDestinationProperty($id);
+    }
+    return implode('.', $id_values);
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityContentBase.php

@@ -0,0 +1,122 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityContentBase.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\TypedData\TypedDataInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * The destination class for all content entities lacking a specific class.
+ */
+class EntityContentBase extends Entity {
+
+  /**
+   * Entity manager.
+   *
+   * @var \Drupal\Core\Entity\EntityManagerInterface
+   */
+  protected $entityManager;
+
+  /**
+   * Constructs a content entity.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin ID for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   The migration entity.
+   * @param \Drupal\Core\Entity\EntityStorageInterface $storage
+   *   The storage for this entity type.
+   * @param array $bundles
+   *   The list of bundles this entity type has.
+   * @param \Drupal\migrate\Plugin\MigratePluginManager $plugin_manager
+   *   The plugin manager.
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   *   The entity manager service.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityStorageInterface $storage, array $bundles, EntityManagerInterface $entity_manager) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $storage, $bundles);
+    $this->entityManager = $entity_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    $entity_type = static::getEntityTypeId($plugin_id);
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('entity.manager')->getStorage($entity_type),
+      array_keys($container->get('entity.manager')->getBundleInfo($entity_type)),
+      $container->get('entity.manager')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    $entity = $this->getEntity($row, $old_destination_id_values);
+    return $this->save($entity, $old_destination_id_values);
+  }
+
+  /**
+   * Save the entity.
+   *
+   * @param \Drupal\Core\Entity\ContentEntityInterface $entity
+   *   The content entity.
+   * @param array $old_destination_id_values
+   *   An array of destination id values.
+   *
+   * @return array
+   *   An array containing the entity id.
+   */
+  protected function save(ContentEntityInterface $entity, array $old_destination_id_values = array()) {
+    $entity->save();
+    return array($entity->id());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $id_key = $this->getKey('id');
+    $ids[$id_key]['type'] = 'integer';
+    return $ids;
+  }
+
+  /**
+   * Update an entity with the new values from row.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   The entity to update.
+   * @param \Drupal\migrate\Row $row
+   *   The row object to update from.
+   */
+  protected function updateEntity(EntityInterface $entity, Row $row) {
+    foreach ($row->getDestination() as $field_name => $values) {
+      $field = $entity->$field_name;
+      if ($field instanceof TypedDataInterface) {
+        $field->setValue($values);
+      }
+    }
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityDateFormat.php

@@ -0,0 +1,34 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityDateFormat.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:date_format"
+ * )
+ */
+class EntityDateFormat extends EntityConfigBase {
+
+  /**
+   * {@inheritdoc}
+   *
+   * @param \Drupal\Core\Datetime\DateFormatInterface $entity
+   *   The date entity.
+   */
+  protected function updateEntityProperty(EntityInterface $entity, array $parents, $value) {
+    if ($parents[0] == 'pattern') {
+      $entity->setPattern($value);
+    }
+    else {
+      parent::updateEntityProperty($entity, $parents, $value);
+    }
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityFieldInstance.php

@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityFieldInstance.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:field_config"
+ * )
+ */
+class EntityFieldInstance extends EntityConfigBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['entity_type']['type'] = 'string';
+    $ids['bundle']['type'] = 'string';
+    $ids['field_name']['type'] = 'string';
+    return $ids;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityFieldStorageConfig.php

@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityFieldStorageConfig.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:field_storage_config"
+ * )
+ */
+class EntityFieldStorageConfig extends EntityConfigBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['entity_type']['type'] = 'string';
+    $ids['field_name']['type'] = 'string';
+    return $ids;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityFile.php

@@ -0,0 +1,245 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityFile.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\StreamWrapper\LocalStream;
+use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Row;
+use Drupal\migrate\MigrateException;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Every migration that uses this destination must have an optional
+ * dependency on the d6_file migration to ensure it runs first.
+ *
+ * @MigrateDestination(
+ *   id = "entity:file"
+ * )
+ */
+class EntityFile extends EntityContentBase {
+
+  /**
+   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
+   */
+  protected $streamWrapperManager;
+
+  /**
+   * @var \Drupal\Core\File\FileSystemInterface
+   */
+  protected $fileSystem;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityStorageInterface $storage, array $bundles, EntityManagerInterface $entity_manager, StreamWrapperManagerInterface $stream_wrappers, FileSystemInterface $file_system) {
+    $configuration += array(
+      'source_base_path' => '',
+      'source_path_property' => 'filepath',
+      'destination_path_property' => 'uri',
+      'move' => FALSE,
+      'urlencode' => FALSE,
+    );
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $storage, $bundles, $entity_manager);
+
+    $this->streamWrapperManager = $stream_wrappers;
+    $this->fileSystem = $file_system;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    $entity_type = static::getEntityTypeId($plugin_id);
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('entity.manager')->getStorage($entity_type),
+      array_keys($container->get('entity.manager')->getBundleInfo($entity_type)),
+      $container->get('entity.manager'),
+      $container->get('stream_wrapper_manager'),
+      $container->get('file_system')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    $file = $row->getSourceProperty($this->configuration['source_path_property']);
+    $destination = $row->getDestinationProperty($this->configuration['destination_path_property']);
+    $source = $this->configuration['source_base_path'] . $file;
+
+    // Ensure the source file exists, if it's a local URI or path.
+    if ($this->isLocalUri($source) && !file_exists($source)) {
+      throw new MigrateException(SafeMarkup::format('File @source does not exist.', ['@source' => $source]));
+    }
+
+    // If the start and end file is exactly the same, there is nothing to do.
+    if ($this->isLocationUnchanged($source, $destination)) {
+      return parent::import($row, $old_destination_id_values);
+    }
+
+    $replace = $this->getOverwriteMode($row);
+    $success = $this->writeFile($source, $destination, $replace);
+    if (!$success) {
+      $dir = $this->getDirectory($destination);
+      if (file_prepare_directory($dir, FILE_CREATE_DIRECTORY)) {
+        $success = $this->writeFile($source, $destination, $replace);
+      }
+      else {
+        throw new MigrateException(SafeMarkup::format('Could not create directory @dir', ['@dir' => $dir]));
+      }
+    }
+
+    if ($success) {
+      return parent::import($row, $old_destination_id_values);
+    }
+    else {
+      throw new MigrateException(SafeMarkup::format('File %source could not be copied to %destination.', ['%source' => $source, '%destination' => $destination]));
+    }
+  }
+
+  /**
+   * Tries to move or copy a file.
+   *
+   * @param string $source
+   *  The source path or URI.
+   * @param string $destination
+   *  The destination path or URI.
+   * @param integer $replace
+   *  FILE_EXISTS_REPLACE (default) or FILE_EXISTS_RENAME.
+   *
+   * @return boolean
+   *  TRUE on success, FALSE on failure.
+   */
+  protected function writeFile($source, $destination, $replace = FILE_EXISTS_REPLACE) {
+    if ($this->configuration['move']) {
+      return (boolean) file_unmanaged_move($source, $destination, $replace);
+    }
+    else {
+      $destination = file_destination($destination, $replace);
+      $source = $this->urlencode($source);
+      return @copy($source, $destination);
+    }
+  }
+
+  /**
+   * Determines how to handle file conflicts.
+   *
+   * @param \Drupal\migrate\Row $row
+   *
+   * @return integer
+   *  Either FILE_EXISTS_REPLACE (default) or FILE_EXISTS_RENAME, depending
+   *  on the current configuration.
+   */
+  protected function getOverwriteMode(Row $row) {
+    if (!empty($this->configuration['rename'])) {
+      $entity_id = $row->getDestinationProperty($this->getKey('id'));
+      if ($entity_id && ($entity = $this->storage->load($entity_id))) {
+        return FILE_EXISTS_RENAME;
+      }
+    }
+    return FILE_EXISTS_REPLACE;
+  }
+
+  /**
+   * Returns the directory component of a URI or path.
+   *
+   * For URIs like public://foo.txt, the full physical path of public://
+   * will be returned, since a scheme by itself will trip up certain file
+   * API functions (such as file_prepare_directory()).
+   *
+   * @param string $uri
+   *  The URI or path.
+   *
+   * @return boolean|string
+   *  The directory component of the path or URI, or FALSE if it could not
+   *  be determined.
+   */
+  protected function getDirectory($uri) {
+    $dir = $this->fileSystem->dirname($uri);
+    if (substr($dir, -3) == '://') {
+      return $this->fileSystem->realpath($dir);
+    }
+    else {
+      return $dir;
+    }
+  }
+
+  /**
+   * Returns if the source and destination URIs represent identical paths.
+   * If either URI is a remote stream, will return FALSE.
+   *
+   * @param string $source
+   *  The source URI.
+   * @param string $destination
+   *  The destination URI.
+   *
+   * @return boolean
+   *  TRUE if the source and destination URIs refer to the same physical path,
+   *  otherwise FALSE.
+   */
+  protected function isLocationUnchanged($source, $destination) {
+    if ($this->isLocalUri($source) && $this->isLocalUri($destination)) {
+      return $this->fileSystem->realpath($source) === $this->fileSystem->realpath($destination);
+    }
+    else {
+      return FALSE;
+    }
+  }
+
+  /**
+   * Returns if the given URI or path is considered local.
+   *
+   * A URI or path is considered local if it either has no scheme component,
+   * or the scheme is implemented by a stream wrapper which extends
+   * \Drupal\Core\StreamWrapper\LocalStream.
+   *
+   * @param string $uri
+   *  The URI or path to test.
+   *
+   * @return boolean
+   */
+  protected function isLocalUri($uri) {
+    $scheme = $this->fileSystem->uriScheme($uri);
+    return $scheme === FALSE || $this->streamWrapperManager->getViaScheme($scheme) instanceof LocalStream;
+  }
+
+  /**
+   * Urlencode all the components of a remote filename.
+   *
+   * @param string $filename
+   *   The filename of the file to be urlencoded.
+   *
+   * @return string
+   *   The urlencoded filename.
+   */
+  protected function urlencode($filename) {
+    // Only apply to a full URL
+    if ($this->configuration['urlencode'] && strpos($filename, '://')) {
+      $components = explode('/', $filename);
+      foreach ($components as $key => $component) {
+        $components[$key] = rawurlencode($component);
+      }
+      $filename = implode('/', $components);
+      // Actually, we don't want certain characters encoded
+      $filename = str_replace('%3A', ':', $filename);
+      $filename = str_replace('%3F', '?', $filename);
+      $filename = str_replace('%26', '&', $filename);
+    }
+    return $filename;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityNodeType.php

@@ -0,0 +1,31 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityNodeType.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:node_type"
+ * )
+ */
+class EntityNodeType extends EntityConfigBase {
+
+  /**
+     * {@inheritdoc}
+     */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    $entity_ids = parent::import($row, $old_destination_id_values);
+    if ($row->getDestinationProperty('create_body')) {
+      $node_type = $this->storage->load(reset($entity_ids));
+      node_add_body_field($node_type, $row->getDestinationProperty('create_body_label'));
+    }
+    return $entity_ids;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityRevision.php

@@ -0,0 +1,74 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityRevision.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity_revision",
+ *   deriver = "Drupal\migrate\Plugin\Derivative\MigrateEntityRevision"
+ * )
+ */
+class EntityRevision extends EntityContentBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static function getEntityTypeId($plugin_id) {
+    // Remove entity_revision:
+    return substr($plugin_id, 16);
+  }
+
+  /**
+   * Get the entity.
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The row object.
+   *
+   * @return \Drupal\Core\Entity\EntityInterface|false
+   *   The entity or false if it can not be created.
+   */
+  protected function getEntity(Row $row, array $old_destination_id_values) {
+    $revision_id = $old_destination_id_values ? reset($old_destination_id_values) : $row->getDestinationProperty($this->getKey('revision'));
+    if (!empty($revision_id) && ($entity = $this->storage->loadRevision($revision_id))) {
+      $entity->setNewRevision(FALSE);
+    }
+    else {
+      $entity_id = $row->getDestinationProperty($this->getKey('id'));
+      $entity = $this->storage->load($entity_id);
+      $entity->enforceIsNew(FALSE);
+      $entity->setNewRevision(TRUE);
+    }
+    $this->updateEntity($entity, $row);
+    $entity->isDefaultRevision(FALSE);
+    return $entity;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function save(ContentEntityInterface $entity, array $old_destination_id_values = array()) {
+    $entity->save();
+    return array($entity->getRevisionId());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    if ($key = $this->getKey('revision')) {
+      $ids[$key]['type'] = 'integer';
+      return $ids;
+    }
+    throw new MigrateException('This entity type does not support revisions.');
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntitySearchPage.php

@@ -0,0 +1,33 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntitySearchPage.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:search_page"
+ * )
+ */
+class EntitySearchPage extends EntityConfigBase {
+
+  /**
+   * Updates the entity with the contents of a row.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   The search page entity.
+   * @param \Drupal\migrate\Row $row
+   *   The row object to update from.
+   */
+  protected function updateEntity(EntityInterface $entity, Row $row) {
+    $entity->setPlugin($row->getDestinationProperty('plugin'));
+    $entity->getPlugin()->setConfiguration($row->getDestinationProperty('configuration'));
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityTaxonomyTerm.php

@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityTaxonomyTerm.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:taxonomy_term"
+ * )
+ */
+class EntityTaxonomyTerm extends EntityContentBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEntity(Row $row, array $old_destination_id_values) {
+    if ($row->isStub()) {
+      $row->setDestinationProperty('name', $this->t('Stub name for source tid:') . $row->getSourceProperty('tid'));
+    }
+    return parent::getEntity($row, $old_destination_id_values);
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityUser.php

@@ -0,0 +1,101 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityUser.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Password\PasswordInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\MigratePassword;
+use Drupal\migrate\Plugin\MigratePluginManager;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:user"
+ * )
+ */
+class EntityUser extends EntityContentBase {
+
+  /**
+   * The password service class.
+   *
+   * @var \Drupal\Core\Password\PasswordInterface
+   */
+  protected $password;
+
+  /**
+   * Builds an user entity destination.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param MigrationInterface $migration
+   *   The migration.
+   * @param EntityStorageInterface $storage
+   *   The storage for this entity type.
+   * @param array $bundles
+   *   The list of bundles this entity type has.
+   * @param \Drupal\migrate\Plugin\MigratePluginManager $plugin_manager
+   *   The migrate plugin manager.
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   *   The entity manager service.
+   * @param \Drupal\Core\Password\PasswordInterface $password
+   *   The password service.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityStorageInterface $storage, array $bundles, EntityManagerInterface $entity_manager, PasswordInterface $password) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $storage, $bundles, $entity_manager);
+    if (isset($configuration['md5_passwords'])) {
+      $this->password = $password;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    $entity_type = static::getEntityTypeId($plugin_id);
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('entity.manager')->getStorage($entity_type),
+      array_keys($container->get('entity.manager')->getBundleInfo($entity_type)),
+      $container->get('entity.manager'),
+      $container->get('password')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   * @throws \Drupal\migrate\MigrateException
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    if ($this->password) {
+      if ($this->password instanceof MigratePassword) {
+        $this->password->enableMd5Prefixing();
+      }
+      else {
+        throw new MigrateException('Password service has been altered by another module, aborting.');
+      }
+    }
+    $ids = parent::import($row, $old_destination_id_values);
+    if ($this->password) {
+      $this->password->disableMd5Prefixing();
+    }
+
+    return $ids;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/EntityViewMode.php

@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\EntityViewMode.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+/**
+ * @MigrateDestination(
+ *   id = "entity:entity_view_mode"
+ * )
+ */
+class EntityViewMode extends EntityConfigBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['targetEntityType']['type'] = 'string';
+    $ids['mode']['type'] = 'string';
+    return $ids;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/Null.php

@@ -0,0 +1,41 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\Null.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateDestination(
+ *   id = "null",
+ *   requirements_met = false
+ * )
+ */
+class Null extends DestinationBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    return array();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields(MigrationInterface $migration = NULL) {
+    return array();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/PerComponentEntityDisplay.php

@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\PerComponentEntityDisplay.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+/**
+ * This class imports one component of an entity display.
+ *
+ * @MigrateDestination(
+ *   id = "component_entity_display"
+ * )
+ */
+class PerComponentEntityDisplay extends ComponentEntityDisplayBase {
+
+  const MODE_NAME = 'view_mode';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEntity($entity_type, $bundle, $view_mode) {
+    return entity_get_display($entity_type, $bundle, $view_mode);
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/PerComponentEntityFormDisplay.php

@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\PerComponentEntityFormDisplay.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+/**
+ * This class imports one component of an entity form display.
+ *
+ * @MigrateDestination(
+ *   id = "component_entity_form_display"
+ * )
+ */
+class PerComponentEntityFormDisplay extends ComponentEntityDisplayBase {
+
+  const MODE_NAME = 'form_mode';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEntity($entity_type, $bundle, $form_mode) {
+    return entity_get_form_display($entity_type, $bundle, $form_mode);
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/UrlAlias.php

@@ -0,0 +1,97 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\UrlAlias.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\Core\Path\AliasStorage;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+
+/**
+ * @MigrateDestination(
+ *   id = "url_alias"
+ * )
+ */
+class UrlAlias extends DestinationBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * The alias storage service.
+   *
+   * @var \Drupal\Core\Path\AliasStorage $aliasStorage
+   */
+  protected $aliasStorage;
+
+  /**
+   * Constructs an entity destination plugin.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param MigrationInterface $migration
+   *   The migration.
+   * @param \Drupal\Core\Path\AliasStorage $alias_storage
+   *   The alias storage service.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, AliasStorage $alias_storage) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
+    $this->aliasStorage = $alias_storage;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('path.alias_storage')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+
+    $path = $this->aliasStorage->save(
+      $row->getDestinationProperty('source'),
+      $row->getDestinationProperty('alias'),
+      $row->getDestinationProperty('langcode'),
+      $old_destination_id_values ? $old_destination_id_values[0] : NULL
+    );
+
+    return array($path['pid']);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['pid']['type'] = 'integer';
+    return $ids;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields(MigrationInterface $migration = NULL) {
+    return [
+      'pid' => 'The path id',
+      'source' => 'The source path.',
+      'alias' => 'The url alias.',
+      'langcode' => 'The language code for the url.',
+    ];
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/destination/UserData.php

@@ -0,0 +1,94 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\destination\UserData.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\destination;
+
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\user\UserData as UserDataStorage;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+
+/**
+ * @MigrateDestination(
+ *   id = "user_data"
+ * )
+ */
+class UserData extends DestinationBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * @var \Drupal\user\UserData
+   */
+  protected $userData;
+
+  /**
+   * Builds an user data entity destination.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   The migration.
+   * @param \Drupal\user\UserData $user_data
+   *   The user data service.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, UserDataStorage $user_data) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
+    $this->userData = $user_data;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('user.data')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    $uid = $row->getDestinationProperty('uid');
+    $module = $row->getDestinationProperty('module');
+    $key = $row->getDestinationProperty('key');
+    $this->userData->set($module, $uid, $key, $row->getDestinationProperty('settings'));
+
+    return [$uid, $module, $key];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['uid']['type'] = 'integer';
+    $ids['module']['type'] = 'string';
+    $ids['key']['type'] = 'string';
+    return $ids;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields(MigrationInterface $migration = NULL) {
+    return [
+      'uid' => 'The user id.',
+      'module' => 'The module name responsible for the settings.',
+      'key' => 'The setting key to save under.',
+      'settings' => 'The settings to save.',
+    ];
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/id_map/Sql.php

@@ -0,0 +1,793 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\id_map\Sql.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\id_map;
+
+use Drupal\Component\Utility\Unicode;
+use Drupal\Core\Database\Connection;
+use Drupal\Core\Field\BaseFieldDefinition;
+use Drupal\Core\Plugin\PluginBase;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\MigrateMessageInterface;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+use Drupal\migrate\Row;
+
+/**
+ * Defines the sql based ID map implementation.
+ *
+ * It creates one map and one message table per migration entity to store the
+ * relevant information.
+ *
+ * @PluginID("sql")
+ */
+class Sql extends PluginBase implements MigrateIdMapInterface {
+
+  /**
+   * The migration map table name.
+   *
+   * @var string
+   */
+  protected $mapTableName;
+
+  /**
+   * The message table name.
+   *
+   * @var string
+   */
+  protected $messageTableName;
+
+  /**
+   * The migrate message.
+   *
+   * @var \Drupal\migrate\MigrateMessageInterface
+   */
+  protected $message;
+
+  /**
+   * The database connection for the map/message tables on the destination.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $database;
+
+  /**
+   * @var \Drupal\Core\Database\Query\SelectInterface
+   */
+  protected $query;
+
+  /**
+   * The migration being done.
+   *
+   * @var \Drupal\migrate\Entity\MigrationInterface
+   */
+  protected $migration;
+
+  /**
+   * The source ID fields.
+   *
+   * @var array
+   */
+  protected $sourceIdFields;
+
+  /**
+   * The destination ID fields.
+   *
+   * @var array
+   */
+  protected $destinationIdFields;
+
+  /**
+   * Whether the plugin is already initialized.
+   *
+   * @var bool
+   */
+  protected $initialized;
+
+  /**
+   * The result.
+   *
+   * @var null
+   */
+  protected $result = NULL;
+
+  /**
+   * The source identifiers.
+   *
+   * @var array
+   */
+  protected $sourceIds = array();
+
+  /**
+   * The destination identifiers.
+   *
+   * @var array
+   */
+  protected $destinationIds = array();
+
+  /**
+   * The current row.
+   *
+   * @var null
+   */
+  protected $currentRow = NULL;
+
+  /**
+   * The current key.
+   *
+   * @var array
+   */
+  protected $currentKey = array();
+
+  /**
+   * Constructs an SQL object.
+   *
+   * Sets up the tables and builds the maps,
+   *
+   * @param array $configuration
+   *   The configuration.
+   * @param string $plugin_id
+   *   The plugin ID for the migration process to do.
+   * @param mixed $plugin_definition
+   *   The configuration for the plugin.
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   The migration to do.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+
+    $this->migration = $migration;
+  }
+
+  /**
+   * The source ID fields.
+   *
+   * @return array
+   *   The source ID fields.
+   */
+  protected function sourceIdFields() {
+    if (!isset($this->sourceIdFields)) {
+      // Build the source and destination identifier maps.
+      $this->sourceIdFields = array();
+      $count = 1;
+      foreach ($this->migration->getSourcePlugin()->getIds() as $field => $schema) {
+        $this->sourceIdFields[$field] = 'sourceid' . $count++;
+      }
+    }
+    return $this->sourceIdFields;
+  }
+
+  /**
+   * The destination ID fields.
+   *
+   * @return array
+   *   The destination ID fields.
+   */
+  protected function destinationIdFields() {
+    if (!isset($this->destinationIdFields)) {
+      $this->destinationIdFields = array();
+      $count = 1;
+      foreach ($this->migration->getDestinationPlugin()->getIds() as $field => $schema) {
+        $this->destinationIdFields[$field] = 'destid' . $count++;
+      }
+    }
+    return $this->destinationIdFields;
+  }
+
+  /**
+   * The name of the database map table.
+   *
+   * @return string
+   *   The map table name.
+   */
+  public function mapTableName() {
+    $this->init();
+    return $this->mapTableName;
+  }
+
+  /**
+   * The name of the database message table.
+   *
+   * @return string
+   *   The message table name.
+   */
+  public function messageTableName() {
+    $this->init();
+    return $this->messageTableName;
+  }
+
+  /**
+   * Get the fully qualified map table name.
+   *
+   * @return string
+   *   The fully qualified map table name.
+   */
+  public function getQualifiedMapTableName() {
+    return $this->getDatabase()->getFullQualifiedTableName($this->mapTableName);
+  }
+
+  /**
+   * Gets the database connection.
+   *
+   * @return \Drupal\Core\Database\Connection
+   *   The database connection object.
+   */
+  public function getDatabase() {
+    if (!isset($this->database)) {
+      $this->database = \Drupal::database();
+    }
+    $this->init();
+    return $this->database;
+  }
+
+  /**
+   * Initialize the plugin.
+   */
+  protected function init() {
+    if (!$this->initialized) {
+      $this->initialized = TRUE;
+      // Default generated table names, limited to 63 characters.
+      $machine_name = str_replace(':', '__', $this->migration->id());
+      $prefix_length = strlen($this->getDatabase()->tablePrefix());
+      $this->mapTableName = 'migrate_map_' . Unicode::strtolower($machine_name);
+      $this->mapTableName = Unicode::substr($this->mapTableName, 0, 63 - $prefix_length);
+      $this->messageTableName = 'migrate_message_' . Unicode::strtolower($machine_name);
+      $this->messageTableName = Unicode::substr($this->messageTableName, 0, 63 - $prefix_length);
+      $this->ensureTables();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setMessage(MigrateMessageInterface $message) {
+    $this->message = $message;
+  }
+
+  /**
+   * Create the map and message tables if they don't already exist.
+   */
+  protected function ensureTables() {
+    if (!$this->getDatabase()->schema()->tableExists($this->mapTableName)) {
+      // Generate appropriate schema info for the map and message tables,
+      // and map from the source field names to the map/msg field names.
+      $count = 1;
+      $source_id_schema = array();
+      $pks = array();
+      foreach ($this->migration->getSourcePlugin()->getIds() as $id_definition) {
+        $mapkey = 'sourceid' . $count++;
+        $source_id_schema[$mapkey] = $this->getFieldSchema($id_definition);
+
+        // With InnoDB, utf8mb4-based primary keys can't be over 191 characters.
+        // Use ASCII-based primary keys instead.
+        if (isset($source_id_schema[$mapkey]['type']) && $source_id_schema[$mapkey]['type'] == 'varchar') {
+          $source_id_schema[$mapkey]['type'] = 'varchar_ascii';
+        }
+        $pks[] = $mapkey;
+      }
+
+      $fields = $source_id_schema;
+
+      // Add destination identifiers to map table.
+      // TODO: How do we discover the destination schema?
+      $count = 1;
+      foreach ($this->migration->getDestinationPlugin()->getIds() as $id_definition) {
+        // Allow dest identifier fields to be NULL (for IGNORED/FAILED
+        // cases).
+        $mapkey = 'destid' . $count++;
+        $fields[$mapkey] = $this->getFieldSchema($id_definition);
+        $fields[$mapkey]['not null'] = FALSE;
+      }
+      $fields['source_row_status'] = array(
+        'type' => 'int',
+        'size' => 'tiny',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => MigrateIdMapInterface::STATUS_IMPORTED,
+        'description' => 'Indicates current status of the source row',
+      );
+      $fields['rollback_action'] = array(
+        'type' => 'int',
+        'size' => 'tiny',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => MigrateIdMapInterface::ROLLBACK_DELETE,
+        'description' => 'Flag indicating what to do for this item on rollback',
+      );
+      $fields['last_imported'] = array(
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'UNIX timestamp of the last time this row was imported',
+      );
+      $fields['hash'] = array(
+        'type' => 'varchar',
+        'length' => '64',
+        'not null' => FALSE,
+        'description' => 'Hash of source row data, for detecting changes',
+      );
+      $schema = array(
+        'description' => 'Mappings from source identifier value(s) to destination identifier value(s).',
+        'fields' => $fields,
+      );
+      if ($pks) {
+        $schema['primary key'] = $pks;
+      }
+      $this->getDatabase()->schema()->createTable($this->mapTableName, $schema);
+
+      // Now do the message table.
+      if (!$this->getDatabase()->schema()->tableExists($this->messageTableName())) {
+        $fields = array();
+        $fields['msgid'] = array(
+          'type' => 'serial',
+          'unsigned' => TRUE,
+          'not null' => TRUE,
+        );
+        $fields += $source_id_schema;
+
+        $fields['level'] = array(
+          'type' => 'int',
+          'unsigned' => TRUE,
+          'not null' => TRUE,
+          'default' => 1,
+        );
+        $fields['message'] = array(
+          'type' => 'text',
+          'size' => 'medium',
+          'not null' => TRUE,
+        );
+        $schema = array(
+          'description' => 'Messages generated during a migration process',
+          'fields' => $fields,
+          'primary key' => array('msgid'),
+        );
+        if ($pks) {
+          $schema['indexes']['sourcekey'] = $pks;
+        }
+        $this->getDatabase()->schema()->createTable($this->messageTableName(), $schema);
+      }
+    }
+    else {
+      // Add any missing columns to the map table.
+      if (!$this->getDatabase()->schema()->fieldExists($this->mapTableName,
+                                                    'rollback_action')) {
+        $this->getDatabase()->schema()->addField($this->mapTableName,
+                                              'rollback_action', array(
+          'type' => 'int',
+          'size' => 'tiny',
+          'unsigned' => TRUE,
+          'not null' => TRUE,
+          'default' => 0,
+          'description' => 'Flag indicating what to do for this item on rollback',
+        ));
+      }
+      if (!$this->getDatabase()->schema()->fieldExists($this->mapTableName, 'hash')) {
+        $this->getDatabase()->schema()->addField($this->mapTableName, 'hash', array(
+          'type' => 'varchar',
+          'length' => '64',
+          'not null' => FALSE,
+          'description' => 'Hash of source row data, for detecting changes',
+        ));
+      }
+    }
+  }
+
+  /**
+   * Create schema from an id definition.
+   *
+   * @param array $id_definition
+   *   A field schema definition. Can be SQL schema or a type data
+   *   based schema. In the latter case, the value of type needs to be
+   *   $typed_data_type.$column
+   * @return array
+   */
+  protected function getFieldSchema(array $id_definition) {
+    $type_parts = explode('.', $id_definition['type']);
+    if (count($type_parts) == 1) {
+      $type_parts[] = 'value';
+    }
+    $schema = BaseFieldDefinition::create($type_parts[0])->getColumns();
+    return $schema[$type_parts[1]];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getRowBySource(array $source_id_values) {
+    $query = $this->getDatabase()->select($this->mapTableName(), 'map')
+              ->fields('map');
+    foreach ($this->sourceIdFields() as $source_id) {
+      $query = $query->condition("map.$source_id", array_shift($source_id_values), '=');
+    }
+    $result = $query->execute();
+    return $result->fetchAssoc();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getRowByDestination(array $destination_id_values) {
+    $query = $this->getDatabase()->select($this->mapTableName(), 'map')
+              ->fields('map');
+    foreach ($this->destinationIdFields() as $destination_id) {
+      $query = $query->condition("map.$destination_id", array_shift($destination_id_values), '=');
+    }
+    $result = $query->execute();
+    return $result->fetchAssoc();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getRowsNeedingUpdate($count) {
+    $rows = array();
+    $result = $this->getDatabase()->select($this->mapTableName(), 'map')
+                      ->fields('map')
+                      ->condition('source_row_status', MigrateIdMapInterface::STATUS_NEEDS_UPDATE)
+                      ->range(0, $count)
+                      ->execute();
+    foreach ($result as $row) {
+      $rows[] = $row;
+    }
+    return $rows;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function lookupSourceID(array $destination_id) {
+    $query = $this->getDatabase()->select($this->mapTableName(), 'map')
+              ->fields('map', $this->sourceIdFields());
+    foreach ($this->destinationIdFields() as $key_name) {
+      $query = $query->condition("map.$key_name", array_shift($destination_id), '=');
+    }
+    $result = $query->execute();
+    $source_id = $result->fetchAssoc();
+    return array_values($source_id ?: array());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function lookupDestinationId(array $source_id) {
+    if (empty($source_id)) {
+      return array();
+    }
+    $query = $this->getDatabase()->select($this->mapTableName(), 'map')
+              ->fields('map', $this->destinationIdFields());
+    foreach ($this->sourceIdFields() as $key_name) {
+      $query = $query->condition("map.$key_name", array_shift($source_id), '=');
+    }
+    $result = $query->execute();
+    $destination_id = $result->fetchAssoc();
+    return array_values($destination_id ?: array());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function saveIdMapping(Row $row, array $destination_id_values, $source_row_status = MigrateIdMapInterface::STATUS_IMPORTED, $rollback_action = MigrateIdMapInterface::ROLLBACK_DELETE) {
+    // Construct the source key.
+    $source_id_values = $row->getSourceIdValues();
+    // Construct the source key and initialize to empty variable keys.
+    $keys = array();
+    foreach ($this->sourceIdFields() as $field_name => $key_name) {
+      // A NULL key value will fail.
+      if (!isset($source_id_values[$field_name])) {
+        $this->message->display(t(
+          'Could not save to map table due to NULL value for key field !field',
+          array('!field' => $field_name)), 'error');
+        return;
+      }
+      $keys[$key_name] = $source_id_values[$field_name];
+    }
+
+    $fields = array(
+      'source_row_status' => (int) $source_row_status,
+      'rollback_action' => (int) $rollback_action,
+      'hash' => $row->getHash(),
+    );
+    $count = 0;
+    foreach ($destination_id_values as $dest_id) {
+      $fields['destid' . ++$count] = $dest_id;
+    }
+    if ($count && $count != count($this->destinationIdFields())) {
+      $this->message->display(t('Could not save to map table due to missing destination id values'), 'error');
+      return;
+    }
+    if ($this->migration->get('trackLastImported')) {
+      $fields['last_imported'] = time();
+    }
+    if ($keys) {
+      $this->getDatabase()->merge($this->mapTableName())
+        ->key($keys)
+        ->fields($fields)
+        ->execute();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function saveMessage(array $source_id_values, $message, $level = MigrationInterface::MESSAGE_ERROR) {
+    $count = 1;
+    foreach ($source_id_values as $id_value) {
+      $fields['sourceid' . $count++] = $id_value;
+      // If any key value is not set, we can't save.
+      if (!isset($id_value)) {
+        return;
+      }
+    }
+    $fields['level'] = $level;
+    $fields['message'] = $message;
+    $this->getDatabase()->insert($this->messageTableName())
+      ->fields($fields)
+      ->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function prepareUpdate() {
+    $this->getDatabase()->update($this->mapTableName())
+    ->fields(array('source_row_status' => MigrateIdMapInterface::STATUS_NEEDS_UPDATE))
+    ->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processedCount() {
+    return $this->getDatabase()->select($this->mapTableName())
+      ->countQuery()
+      ->execute()
+      ->fetchField();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function importedCount() {
+    return $this->getDatabase()->select($this->mapTableName())
+      ->condition('source_row_status', array(MigrateIdMapInterface::STATUS_IMPORTED, MigrateIdMapInterface::STATUS_NEEDS_UPDATE), 'IN')
+      ->countQuery()
+      ->execute()
+      ->fetchField();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function updateCount() {
+    return $this->countHelper(MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function errorCount() {
+    return $this->countHelper(MigrateIdMapInterface::STATUS_FAILED);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function messageCount() {
+    return $this->countHelper(NULL, $this->messageTableName());
+  }
+
+  /**
+   * Counts records in a table.
+   *
+   * @param $status
+   *   An integer for the source_row_status column.
+   * @param $table
+   *   The table to work
+   * @return int
+   *   The number of records.
+   */
+  protected function countHelper($status, $table = NULL) {
+    $query = $this->getDatabase()->select($table ?: $this->mapTableName());
+    if (isset($status)) {
+      $query->condition('source_row_status', $status);
+    }
+    return $query->countQuery()->execute()->fetchField();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function delete(array $source_id_values, $messages_only = FALSE) {
+    if (empty($source_id_values)) {
+      throw new MigrateException('Without source identifier values it is impossible to find the row to delete.');
+    }
+    if (!$messages_only) {
+      $map_query = $this->getDatabase()->delete($this->mapTableName());
+    }
+    $message_query = $this->getDatabase()->delete($this->messageTableName());
+    $count = 1;
+    foreach ($source_id_values as $id_value) {
+      if (!$messages_only) {
+        $map_query->condition('sourceid' . $count, $id_value);
+      }
+      $message_query->condition('sourceid' . $count, $id_value);
+      $count++;
+    }
+
+    if (!$messages_only) {
+      $map_query->execute();
+    }
+    $message_query->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteDestination(array $destination_id) {
+    $map_query = $this->getDatabase()->delete($this->mapTableName());
+    $message_query = $this->getDatabase()->delete($this->messageTableName());
+    $source_id = $this->lookupSourceID($destination_id);
+    if (!empty($source_id)) {
+      $count = 1;
+      foreach ($destination_id as $key_value) {
+        $map_query->condition('destid' . $count, $key_value);
+        $count++;
+      }
+      $map_query->execute();
+      $count = 1;
+      foreach ($source_id as $key_value) {
+        $message_query->condition('sourceid' . $count, $key_value);
+        $count++;
+      }
+      $message_query->execute();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUpdate(array $source_id) {
+    if (empty($source_id)) {
+      throw new MigrateException('No source identifiers provided to update.');
+    }
+    $query = $this->getDatabase()
+      ->update($this->mapTableName())
+      ->fields(array('source_row_status' => MigrateIdMapInterface::STATUS_NEEDS_UPDATE));
+    $count = 1;
+    foreach ($source_id as $key_value) {
+      $query->condition('sourceid' . $count++, $key_value);
+    }
+    $query->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteBulk(array $source_id_values) {
+    // If we have a single-column key, we can shortcut it.
+    if (count($this->migration->getSourcePlugin()->getIds()) == 1) {
+      $sourceids = array();
+      foreach ($source_id_values as $source_id) {
+        $sourceids[] = $source_id;
+      }
+      $this->getDatabase()->delete($this->mapTableName())
+        ->condition('sourceid1', $sourceids, 'IN')
+        ->execute();
+      $this->getDatabase()->delete($this->messageTableName())
+        ->condition('sourceid1', $sourceids, 'IN')
+        ->execute();
+    }
+    else {
+      foreach ($source_id_values as $source_id) {
+        $map_query = $this->getDatabase()->delete($this->mapTableName());
+        $message_query = $this->getDatabase()->delete($this->messageTableName());
+        $count = 1;
+        foreach ($source_id as $key_value) {
+          $map_query->condition('sourceid' . $count, $key_value);
+          $message_query->condition('sourceid' . $count++, $key_value);
+        }
+        $map_query->execute();
+        $message_query->execute();
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function clearMessages() {
+    $this->getDatabase()->truncate($this->messageTableName())->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function destroy() {
+    $this->getDatabase()->schema()->dropTable($this->mapTableName());
+    $this->getDatabase()->schema()->dropTable($this->messageTableName());
+  }
+
+  /**
+   * Implementation of Iterator::rewind().
+   *
+   * This is called before beginning a foreach loop.
+   *
+   * @todo Support idlist, itemlimit.
+   */
+  public function rewind() {
+    $this->currentRow = NULL;
+    $fields = array();
+    foreach ($this->sourceIdFields() as $field) {
+      $fields[] = $field;
+    }
+    foreach ($this->destinationIdFields() as $field) {
+      $fields[] = $field;
+    }
+
+    // @todo Make this work.
+    /*
+    if (isset($this->options['itemlimit'])) {
+      $query = $query->range(0, $this->options['itemlimit']);
+    }
+    */
+    $this->result = $this->getDatabase()->select($this->mapTableName(), 'map')
+      ->fields('map', $fields)
+      ->execute();
+    $this->next();
+  }
+
+  /**
+   * Implementation of Iterator::current().
+   *
+   * This is called when entering a loop iteration, returning the current row.
+   */
+  public function current() {
+    return $this->currentRow;
+  }
+
+  /**
+   * Implementation of Iterator::key().
+   *
+   * This is called when entering a loop iteration, returning the key of the
+   * current row. It must be a scalar - we will serialize to fulfill the
+   * requirement, but using getCurrentKey() is preferable.
+   */
+  public function key() {
+    return serialize($this->currentKey);
+  }
+
+  /**
+   * Implementation of Iterator::next().
+   *
+   * This is called at the bottom of the loop implicitly, as well as explicitly
+   * from rewind().
+   */
+  public function next() {
+    $this->currentRow = $this->result->fetchAssoc();
+    $this->currentKey = array();
+    if ($this->currentRow) {
+      foreach ($this->sourceIdFields() as $map_field) {
+        $this->currentKey[$map_field] = $this->currentRow[$map_field];
+        // Leave only destination fields.
+        unset($this->currentRow[$map_field]);
+      }
+    }
+  }
+
+  /**
+   * Implementation of Iterator::valid().
+   *
+   * This is called at the top of the loop, returning TRUE to process the loop
+   * and FALSE to terminate it.
+   */
+  public function valid() {
+    // @todo Check numProcessed against itemlimit.
+    return $this->currentRow !== FALSE;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/Callback.php

@@ -0,0 +1,39 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\Callback.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\Row;
+
+/**
+ * This plugin allows source value to be passed to a callback.
+ *
+ * The current value is passed to a callable that returns the processed value.
+ * This plugin allows simple processing of the value, such as strtolower(). The
+ * callable takes the value as the single mandatory argument. No additional
+ * arguments can be passed to the callback as this would make the migration YAML
+ * file too complex.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "callback"
+ * )
+ */
+class Callback extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    if (is_callable($this->configuration['callable'])) {
+      $value = call_user_func($this->configuration['callable'], $value);
+    }
+    return $value;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/Concat.php

@@ -0,0 +1,41 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\Concat.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\Component\Utility\SafeMarkup;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\Row;
+
+/**
+ * Concatenates the strings in the current value.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "concat",
+ *   handle_multiples = TRUE
+ * )
+ */
+class Concat extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   *
+   * Concatenates the strings in the current value.
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    if (is_array($value)) {
+      $delimiter = isset($this->configuration['delimiter']) ? $this->configuration['delimiter'] : '';
+      return implode($delimiter, $value);
+    }
+    else {
+      throw new MigrateException(sprintf('%s is not an array', SafeMarkup::checkPlain(var_export($value, TRUE))));
+    }
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/DedupeBase.php

@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\DedupeBase.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+use Drupal\migrate\MigrateException;
+use Drupal\Component\Utility\Unicode;
+
+/**
+ * This abstract base contains the dedupe logic.
+ *
+ * These plugins avoid duplication at the destination. For example, when
+ * creating filter format names, the current value is checked against the
+ * existing filter format names and if it exists, a numeric postfix is added
+ * and incremented until a unique value is created.
+ */
+abstract class DedupeBase extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    $i = 1;
+    $postfix = isset($this->configuration['postfix']) ? $this->configuration['postfix'] : '';
+    $start = isset($this->configuration['start']) ? $this->configuration['start'] : 0;
+    if (!is_int($start)) {
+      throw new MigrateException('The start position configuration key should be an integer. Omit this key to capture from the beginning of the string.');
+    }
+    $length = isset($this->configuration['length']) ? $this->configuration['length'] : NULL;
+    if (!is_null($length) && !is_int($length)) {
+      throw new MigrateException('The character length configuration key should be an integer. Omit this key to capture the entire string.');
+    }
+    // Use optional start or length to return a portion of deduplicated value.
+    $value = Unicode::substr($value, $start, $length);
+    $new_value = $value;
+    while ($this->exists($new_value)) {
+      $new_value = $value . $postfix . $i++;
+    }
+    return $new_value;
+  }
+
+  /**
+   * This is a query checking the existence of some value.
+   *
+   * @param mixed $value
+   *   The value to check.
+   *
+   * @return bool
+   *   TRUE if the value exists.
+   */
+  abstract protected function exists($value);
+
+}

core/modules/migrate/src/Plugin/migrate/process/DedupeEntity.php

@@ -0,0 +1,63 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\DedupeEntity.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\Core\Entity\Query\QueryFactory;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Ensures value is not duplicated against an entity field.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "dedupe_entity"
+ * )
+ */
+class DedupeEntity extends DedupeBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * @var \Drupal\Core\Entity\Query\QueryFactoryInterface
+   */
+  protected $entityQueryFactory;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, QueryFactory $entity_query_factory) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->entityQueryFactory = $entity_query_factory;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('entity.query')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function exists($value) {
+    // Plugins are cached so for every run we need a new query object.
+    return $this
+      ->entityQueryFactory
+      ->get($this->configuration['entity_type'], 'AND')
+      ->condition($this->configuration['field'], $value)
+      ->count()
+      ->execute();
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/DefaultValue.php

@@ -0,0 +1,33 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\DefaultValue.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+
+
+/**
+ * This plugin sets missing values on the destination.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "default_value"
+ * )
+ */
+class DefaultValue extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    if (!empty($this->configuration['strict'])) {
+      return isset($value) ? $value : $this->configuration['default_value'];
+    }
+    return $value ?: $this->configuration['default_value'];
+  }
+}

core/modules/migrate/src/Plugin/migrate/process/Extract.php

@@ -0,0 +1,41 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\Extract.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\Component\Utility\NestedArray;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+
+/**
+ * This plugin extracts a value from an array.
+ *
+ * @see https://www.drupal.org/node/2152731
+ *
+ * @MigrateProcessPlugin(
+ *   id = "extract"
+ * )
+ */
+class Extract extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    if (!is_array($value)) {
+      throw new MigrateException('Input should be an array.');
+    }
+    $new_value = NestedArray::getValue($value, $this->configuration['index'], $key_exists);
+    if (!$key_exists) {
+      throw new MigrateException('Array index missing, extraction failed.');
+    }
+    return $new_value;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/Flatten.php

@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\Flatten.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\Row;
+
+/**
+ * This plugin flattens the current value.
+ *
+ * During some types of processing (e.g. user permission splitting), what was
+ * once a single value gets transformed into multiple values. This plugin will
+ * flatten them back down to single values again.
+ *
+ * @see https://www.drupal.org/node/2154215
+ *
+ * @MigrateProcessPlugin(
+ *   id = "flatten",
+ *   handle_multiples = TRUE
+ * )
+ */
+class Flatten extends ProcessPluginBase {
+
+  /**
+   * Flatten nested array values to single array values.
+   *
+   * For example, array(array(1, 2, array(3, 4))) becomes array(1, 2, 3, 4).
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    return iterator_to_array(new \RecursiveIteratorIterator(new \RecursiveArrayIterator($value)), FALSE);
+  }
+}

core/modules/migrate/src/Plugin/migrate/process/Get.php

@@ -0,0 +1,72 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\Get.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+
+/**
+ * This plugin copies from the source to the destination.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "get"
+ * )
+ */
+class Get extends ProcessPluginBase {
+
+  /**
+   * @var bool
+   */
+  protected $multiple;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    $source = $this->configuration['source'];
+    $properties = is_string($source) ? array($source) : $source;
+    $return = array();
+    foreach ($properties as $property) {
+      if (empty($property)) {
+        $return[] = $value;
+      }
+      else {
+        $is_source = TRUE;
+        if ($property[0] == '@') {
+          $property = preg_replace_callback('/^(@?)((?:@@)*)([^@]|$)/', function ($matches) use (&$is_source) {
+            // If there are an odd number of @ in the beginning, it's a
+            // destination.
+            $is_source = empty($matches[1]);
+            // Remove the possible escaping and do not lose the terminating
+            // non-@ either.
+            return str_replace('@@', '@', $matches[2]) . $matches[3];
+          }, $property);
+        }
+        if ($is_source) {
+          $return[] = $row->getSourceProperty($property);
+        }
+        else {
+          $return[] = $row->getDestinationProperty($property);
+        }
+      }
+    }
+    if (is_string($source)) {
+      $this->multiple = is_array($return[0]);
+      return $return[0];
+    }
+    return $return;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function multiple() {
+    return $this->multiple;
+  }
+}

core/modules/migrate/src/Plugin/migrate/process/Iterator.php

@@ -0,0 +1,68 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\Iterator.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+
+/**
+ * This plugin iterates and processes an array.
+ *
+ * @see https://www.drupal.org/node/2135345
+ *
+ * @MigrateProcessPlugin(
+ *   id = "iterator",
+ *   handle_multiples = TRUE
+ * )
+ */
+class Iterator extends ProcessPluginBase {
+
+  /**
+   * Runs a process pipeline on each destination property per list item.
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    $return = array();
+    foreach ($value as $key => $new_value) {
+      $new_row = new Row($new_value, array());
+      $migrate_executable->processRow($new_row, $this->configuration['process']);
+      $destination = $new_row->getDestination();
+      if (array_key_exists('key', $this->configuration)) {
+        $key = $this->transformKey($key, $migrate_executable, $new_row);
+      }
+      $return[$key] = $destination;
+    }
+    return $return;
+  }
+
+  /**
+   * Runs the process pipeline for the current key.
+   *
+   * @param string|int $key
+   *   The current key.
+   * @param \Drupal\migrate\MigrateExecutableInterface $migrate_executable
+   *   The migrate executable helper class.
+   * @param \Drupal\migrate\Row $row
+   *   The current row after processing.
+   *
+   * @return mixed
+   *   The transformed key.
+   */
+  protected function transformKey($key, MigrateExecutableInterface $migrate_executable, Row $row) {
+    $process = array('key' => $this->configuration['key']);
+    $migrate_executable->processRow($row, $process, $key);
+    return $row->getDestinationProperty('key');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function multiple() {
+    return TRUE;
+  }
+}

core/modules/migrate/src/Plugin/migrate/process/MachineName.php

@@ -0,0 +1,75 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\MachineName.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\Component\Transliteration\TransliterationInterface;
+use Drupal\Core\Language\LanguageInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * This plugin creates a machine name.
+ *
+ * The current value gets transliterated, non-alphanumeric characters removed
+ * and replaced by an underscore and multiple underscores are collapsed into
+ * one.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "machine_name"
+ * )
+ */
+class MachineName extends ProcessPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * @var \Drupal\Component\Transliteration\TransliterationInterface
+   */
+  protected $transliteration;
+
+  /**
+   * Constructs a MachineName plugin.
+   *
+   * @param array $configuration
+   *  The plugin configuration.
+   * @param string $plugin_id
+   *  The plugin ID.
+   * @param mixed $plugin_definition
+   *  The plugin definition.
+   * @param \Drupal\Component\Transliteration\TransliterationInterface $transliteration
+   *  The transliteration service.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, TransliterationInterface $transliteration) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->transliteration = $transliteration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('transliteration')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    $new_value = $this->transliteration->transliterate($value, LanguageInterface::LANGCODE_DEFAULT, '_');
+    $new_value = strtolower($new_value);
+    $new_value = preg_replace('/[^a-z0-9_]+/', '_', $new_value);
+    return preg_replace('/_+/', '_', $new_value);
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/Migration.php

@@ -0,0 +1,165 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\Migration.
+ */
+
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\migrate\MigrateSkipProcessException;
+use Drupal\migrate\MigrateSkipRowException;
+use Drupal\migrate\Plugin\MigratePluginManager;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Calculates the value of a property based on a previous migration.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "migration"
+ * )
+ */
+class Migration extends ProcessPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * @var \Drupal\migrate\Plugin\MigratePluginManager
+   */
+  protected $processPluginManager;
+
+  /**
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  protected $migrationStorage;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityStorageInterface $storage, MigratePluginManager $process_plugin_manager) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->migrationStorage = $storage;
+    $this->migration = $migration;
+    $this->processPluginManager = $process_plugin_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('entity.manager')->getStorage('migration'),
+      $container->get('plugin.manager.migrate.process')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    $migration_ids = $this->configuration['migration'];
+    if (!is_array($migration_ids)) {
+      $migration_ids = array($migration_ids);
+    }
+    $scalar = FALSE;
+    if (!is_array($value)) {
+      $scalar = TRUE;
+      $value = array($value);
+    }
+    $this->skipOnEmpty($value);
+    $self = FALSE;
+    /** @var \Drupal\migrate\Entity\MigrationInterface[] $migrations */
+    $migrations = $this->migrationStorage->loadMultiple($migration_ids);
+    $destination_ids = NULL;
+    $source_id_values = array();
+    foreach ($migrations as $migration_id => $migration) {
+      if ($migration_id == $this->migration->id()) {
+        $self = TRUE;
+      }
+      if (isset($this->configuration['source_ids'][$migration_id])) {
+        $configuration = array('source' => $this->configuration['source_ids'][$migration_id]);
+        $source_id_values[$migration_id] = $this->processPluginManager
+          ->createInstance('get', $configuration, $this->migration)
+          ->transform(NULL, $migrate_executable, $row, $destination_property);
+      }
+      else {
+        $source_id_values[$migration_id] = $value;
+      }
+      // Break out of the loop as soon as a destination ID is found.
+      if ($destination_ids = $migration->getIdMap()->lookupDestinationID($source_id_values[$migration_id])) {
+        break;
+      }
+    }
+
+    if (!$destination_ids && ($self || isset($this->configuration['stub_id']) || count($migrations) == 1)) {
+      // If the lookup didn't succeed, figure out which migration will do the
+      // stubbing.
+      if ($self) {
+        $migration = $this->migration;
+      }
+      elseif (isset($this->configuration['stub_id'])) {
+        $migration = $migrations[$this->configuration['stub_id']];
+      }
+      else {
+        $migration = reset($migrations);
+      }
+      $destination_plugin = $migration->getDestinationPlugin(TRUE);
+      // Only keep the process necessary to produce the destination ID.
+      $process = $migration->get('process');
+      // We already have the source id values but need to key them for the Row
+      // constructor.
+      $source_ids = $migration->getSourcePlugin()->getIds();
+      $values = array();
+      foreach (array_keys($source_ids) as $index => $source_id) {
+        $values[$source_id] = $source_id_values[$migration->id()][$index];
+      }
+
+      $stub_row = new Row($values + $migration->get('source'), $source_ids, TRUE);
+
+      // Do a normal migration with the stub row.
+      $migrate_executable->processRow($stub_row, $process);
+      $destination_ids = array();
+      try {
+        $destination_ids = $destination_plugin->import($stub_row);
+      }
+      catch (\Exception $e) {
+        $migrate_executable->saveMessage($e->getMessage());
+      }
+    }
+    if ($destination_ids) {
+      if ($scalar) {
+        if (count($destination_ids) == 1) {
+          return reset($destination_ids);
+        }
+      }
+      else {
+        return $destination_ids;
+      }
+    }
+    throw new MigrateSkipRowException();
+  }
+
+  /**
+   * Skip the migration process entirely if the value is FALSE.
+   *
+   * @param mixed $value
+   *   The incoming value to transform.
+   *
+   * @throws \Drupal\migrate\MigrateSkipProcessException
+   */
+  protected function skipOnEmpty($value) {
+    if (!array_filter($value)) {
+      throw new MigrateSkipProcessException();
+    }
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/Route.php

@@ -0,0 +1,93 @@
+<?php
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\Route.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\Core\Path\PathValidatorInterface;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\Row;
+
+/**
+ * @MigrateProcessPlugin(
+ *   id = "route"
+ * )
+ */
+class Route extends ProcessPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * @var \Drupal\Core\Path\PathValidatorInterface
+   */
+  protected $pathValidator;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, PathValidatorInterface $pathValidator) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->migration = $migration;
+    $this->pathValidator = $pathValidator;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('path.validator')
+    );
+  }
+  /**
+   * {@inheritdoc}
+   *
+   * Set the destination route information based on the source link_path.
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    list($link_path, $options) = $value;
+    $extracted = $this->pathValidator->getUrlIfValidWithoutAccessCheck($link_path);
+    $route = array();
+
+    if ($extracted) {
+      if ($extracted->isExternal()) {
+        $route['route_name'] = null;
+        $route['route_parameters'] = array();
+        $route['options'] = $options;
+        $route['url'] = $extracted->getUri();
+      }
+      else {
+        $route['route_name'] = $extracted->getRouteName();
+        $route['route_parameters'] = $extracted->getRouteParameters();
+        $route['options'] = $extracted->getOptions();
+
+        if (isset($options['query'])) {
+          // If the querystring is stored as a string (as in D6), convert it
+          // into an array.
+          if (is_string($options['query'])) {
+            parse_str($options['query'], $old_query);
+          }
+          else {
+            $old_query = $options['query'];
+          }
+          $options['query'] = $route['options']['query'] + $old_query;
+          unset($route['options']['query']);
+        }
+        $route['options'] = $route['options'] + $options;
+        $route['url'] = null;
+      }
+    }
+
+    return $route;
+  }
+
+}
+

core/modules/migrate/src/Plugin/migrate/process/SkipOnEmpty.php

@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\SkipOnEmpty.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\migrate\MigrateSkipProcessException;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+use Drupal\migrate\MigrateSkipRowException;
+
+/**
+ * If the source evaluates to empty, we skip processing or the whole row.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "skip_on_empty"
+ * )
+ */
+class SkipOnEmpty extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function row($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    if (!$value) {
+      throw new MigrateSkipRowException();
+    }
+    return $value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function process($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    if (!$value) {
+      throw new MigrateSkipProcessException();
+    }
+    return $value;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/SkipRowIfNotSet.php

@@ -0,0 +1,35 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\SkipRowIfNotSet.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+use Drupal\migrate\MigrateSkipRowException;
+
+/**
+ * If the source evaluates to empty, we skip the current row.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "skip_row_if_not_set",
+ *   handle_multiples = TRUE
+ * )
+ */
+class SkipRowIfNotSet extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    if (!isset($value[$this->configuration['index']])) {
+      throw new MigrateSkipRowException();
+    }
+    return $value[$this->configuration['index']];
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/process/StaticMap.php

@@ -0,0 +1,59 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\process\StaticMap.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\Component\Utility\NestedArray;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+use Drupal\migrate\MigrateSkipRowException;
+
+/**
+ * This plugin changes the current value based on a static lookup map.
+ *
+ * @see https://www.drupal.org/node/2143521
+ *
+ * @MigrateProcessPlugin(
+ *   id = "static_map"
+ * )
+ */
+class StaticMap extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    $new_value = $value;
+    if (is_array($value)) {
+      if (!$value) {
+        throw new MigrateException('Can not lookup without a value.');
+      }
+    }
+    else {
+      $new_value = array($value);
+    }
+    $new_value = NestedArray::getValue($this->configuration['map'], $new_value, $key_exists);
+    if (!$key_exists) {
+      if (isset($this->configuration['default_value'])) {
+        if (!empty($this->configuration['bypass'])) {
+          throw new MigrateException('Setting both default_value and bypass is invalid.');
+        }
+        return $this->configuration['default_value'];
+      }
+      if (empty($this->configuration['bypass'])) {
+        throw new MigrateSkipRowException();
+      }
+      else {
+        return $value;
+      }
+    }
+    return $new_value;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/source/EmptySource.php

@@ -0,0 +1,56 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\source\EmptySource.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\source;
+
+/**
+ * Source returning an empty row.
+ *
+ * This is generally useful when needing to create a field using a migration..
+ *
+ * @MigrateSource(
+ *   id = "empty"
+ * )
+ */
+class EmptySource extends SourcePluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields() {
+    return array(
+      'id' => t('ID'),
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function initializeIterator() {
+    return new \ArrayIterator(array(array('id' => '')));
+  }
+
+  public function __toString() {
+    return '';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['id']['type'] = 'string';
+    return $ids;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function count() {
+    return 1;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php

@@ -0,0 +1,458 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\source\SourcePluginBase.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\source;
+
+use Drupal\Core\Plugin\PluginBase;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+use Drupal\migrate\Plugin\MigrateSourceInterface;
+use Drupal\migrate\Row;
+
+/**
+ * The base class for all source plugins.
+ *
+ * @see \Drupal\migrate\Plugin\MigratePluginManager
+ * @see \Drupal\migrate\Annotation\MigrateSource
+ * @see \Drupal\migrate\Plugin\MigrateSourceInterface
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+abstract class SourcePluginBase extends PluginBase implements MigrateSourceInterface {
+
+  /**
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
+   */
+  protected $moduleHandler;
+
+  /**
+   * @var \Drupal\migrate\Entity\MigrationInterface
+   */
+  protected $migration;
+
+  /**
+   * The name and type of the highwater property in the source.
+   *
+   * @var array
+   *
+   * @see $originalHighwater
+   */
+  protected $highWaterProperty;
+
+  /**
+   * The current row from the query
+   *
+   * @var \Drupal\Migrate\Row
+   */
+  protected $currentRow;
+
+  /**
+   * The primary key of the current row
+   *
+   * @var array
+   */
+  protected $currentSourceIds;
+
+  /**
+   * Number of rows intentionally ignored (prepareRow() returned FALSE)
+   *
+   * @var int
+   */
+  protected $numIgnored = 0;
+
+  /**
+   * Number of rows we've at least looked at.
+   *
+   * @var int
+   */
+  protected $numProcessed = 0;
+
+  /**
+   * The high water mark at the beginning of the import operation.
+   *
+   * If the source has a property for tracking changes (like Drupal ha
+   * node.changed) then this is the highest value of those imported so far.
+   *
+   * @var int
+   */
+  protected $originalHighWater;
+
+  /**
+   * List of source IDs to process.
+   *
+   * @var array
+   */
+  protected $idList = array();
+
+  /**
+   * Whether this instance should cache the source count.
+   *
+   * @var bool
+   */
+  protected $cacheCounts = FALSE;
+
+  /**
+   * Key to use for caching counts.
+   *
+   * @var string
+   */
+  protected $cacheKey;
+
+  /**
+   * Whether this instance should not attempt to count the source.
+   *
+   * @var bool
+   */
+  protected $skipCount = FALSE;
+
+  /**
+   * If TRUE, we will maintain hashed source rows to determine whether incoming
+   * data has changed.
+   *
+   * @var bool
+   */
+  protected $trackChanges = FALSE;
+
+  /**
+   * By default, next() will directly read the map row and add it to the data
+   * row. A source plugin implementation may do this itself (in particular, the
+   * SQL source can incorporate the map table into the query) - if so, it should
+   * set this TRUE so we don't duplicate the effort.
+   *
+   * @var bool
+   */
+  protected $mapRowAdded = FALSE;
+
+  /**
+   * @var \Drupal\Core\Cache\CacheBackendInterface
+   */
+  protected $cache;
+
+  /**
+   * @var \Drupal\migrate\Plugin\MigrateIdMapInterface
+   */
+  protected $idMap;
+
+  /**
+   * @var \Iterator
+   */
+  protected $iterator;
+
+  // @TODO, find out how to remove this.
+  // @see https://www.drupal.org/node/2443617
+  public $migrateExecutable;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->migration = $migration;
+
+    // Set up some defaults based on the source configuration.
+    $this->cacheCounts = !empty($configuration['cache_counts']);
+    $this->skipCount = !empty($configuration['skip_count']);
+    $this->cacheKey = !empty($configuration['cache_key']) ? !empty($configuration['cache_key']) : NULL;
+    $this->trackChanges = !empty($configuration['track_changes']) ? $configuration['track_changes'] : FALSE;
+
+    // Pull out the current highwater mark if we have a highwater property.
+    if ($this->highWaterProperty = $this->migration->get('highWaterProperty')) {
+      $this->originalHighWater = $this->migration->getHighWater();
+    }
+
+    if ($id_list = $this->migration->get('idlist')) {
+      $this->idList = $id_list;
+    }
+
+    // Don't allow the use of both highwater and track changes together.
+    if ($this->highWaterProperty && $this->trackChanges) {
+      throw new MigrateException('You should either use a highwater mark or track changes not both. They are both designed to solve the same problem');
+    }
+  }
+
+  /**
+   * Initialize the iterator with the source data.
+   *
+   * @return array
+   *   An array of the data for this source.
+   */
+  protected abstract function initializeIterator();
+
+  /**
+   * Get the module handler.
+   *
+   * @return \Drupal\Core\Extension\ModuleHandlerInterface
+   *   The module handler.
+   */
+  protected function getModuleHandler() {
+    if (!isset($this->moduleHandler)) {
+      $this->moduleHandler = \Drupal::moduleHandler();
+    }
+    return $this->moduleHandler;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function prepareRow(Row $row) {
+
+    $result = TRUE;
+    $result_hook = $this->getModuleHandler()->invokeAll('migrate_prepare_row', array($row, $this, $this->migration));
+    $result_named_hook = $this->getModuleHandler()->invokeAll('migrate_' . $this->migration->id() . '_prepare_row', array($row, $this, $this->migration));
+
+    // We're explicitly skipping this row - keep track in the map table.
+    if (($result_hook && in_array(FALSE, $result_hook)) || ($result_named_hook && in_array(FALSE, $result_named_hook))) {
+      // Make sure we replace any previous messages for this item with any
+      // new ones.
+      $id_map = $this->migration->getIdMap();
+      $id_map->delete($this->currentSourceIds, TRUE);
+      $this->migrateExecutable->saveQueuedMessages();
+      $id_map->saveIdMapping($row, array(), MigrateIdMapInterface::STATUS_IGNORED, $this->migrateExecutable->rollbackAction);
+      $this->numIgnored++;
+      $this->currentRow = NULL;
+      $this->currentSourceIds = NULL;
+      $result = FALSE;
+    }
+    elseif ($this->trackChanges) {
+      // When tracking changed data, We want to quietly skip (rather than
+      // "ignore") rows with changes. The caller needs to make that decision,
+      // so we need to provide them with the necessary information (before and
+      // after hashes).
+      $row->rehash();
+    }
+    $this->numProcessed++;
+    return $result;
+  }
+
+  /**
+   * Returns the iterator that will yield the row arrays to be processed.
+   *
+   * @return \Iterator
+   */
+  public function getIterator() {
+    if (!isset($this->iterator)) {
+      $this->iterator = $this->initializeIterator();
+    }
+    return $this->iterator;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function current() {
+    return $this->currentRow;
+  }
+
+  /**
+   * Get the iterator key.
+   *
+   * Implementation of Iterator::key - called when entering a loop iteration,
+   * returning the key of the current row. It must be a scalar - we will
+   * serialize to fulfill the requirement, but using getCurrentIds() is
+   * preferable.
+   */
+  public function key() {
+    return serialize($this->currentSourceIds);
+  }
+
+  /**
+   * Whether the iterator is currently valid.
+   *
+   * Implementation of Iterator::valid() - called at the top of the loop,
+   * returning TRUE to process the loop and FALSE to terminate it
+   */
+  public function valid() {
+    return isset($this->currentRow);
+  }
+
+  /**
+   * Rewind the iterator.
+   *
+   * Implementation of Iterator::rewind() - subclasses of MigrateSource should
+   * implement performRewind() to do any class-specific setup for iterating
+   * source records.
+   */
+  public function rewind() {
+    $this->idMap = $this->migration->getIdMap();
+    $this->numProcessed = 0;
+    $this->numIgnored = 0;
+    $this->getIterator()->rewind();
+    $this->next();
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * The migration iterates over rows returned by the source plugin. This
+   * method determines the next row which will be processed and imported into
+   * the system.
+   *
+   * The method tracks the source and destination IDs using the ID map plugin.
+   *
+   * This also takes care about highwater support. Highwater allows to reimport
+   * rows from a previous migration run, which got changed in the meantime.
+   * This is done by specifying a highwater field, which is compared with the
+   * last time, the migration got executed (originalHighWater).
+   */
+  public function next() {
+    $this->currentSourceIds = NULL;
+    $this->currentRow = NULL;
+
+    // In order to find the next row we want to process, we ask the source
+    // plugin for the next possible row.
+    while (!isset($this->currentRow) && $this->getIterator()->valid()) {
+
+      $row_data = $this->getIterator()->current() + $this->configuration;
+      $this->getIterator()->next();
+      $row = new Row($row_data, $this->migration->getSourcePlugin()->getIds(), $this->migration->get('destinationIds'));
+
+      // Populate the source key for this row.
+      $this->currentSourceIds = $row->getSourceIdValues();
+
+      // Pick up the existing map row, if any, unless getNextRow() did it.
+      if (!$this->mapRowAdded && ($id_map = $this->idMap->getRowBySource($this->currentSourceIds))) {
+        $row->setIdMap($id_map);
+      }
+
+      // In case we have specified an ID list, but the ID given by the source is
+      // not in there, we skip the row.
+      $id_in_the_list = $this->idList && in_array(reset($this->currentSourceIds), $this->idList);
+      if ($this->idList && !$id_in_the_list) {
+        continue;
+      }
+
+      // Preparing the row gives source plugins the chance to skip.
+      if ($this->prepareRow($row) === FALSE) {
+        continue;
+      }
+
+      // Check whether the row needs processing.
+      // 1. Explicitly specified IDs.
+      // 2. This row has not been imported yet.
+      // 3. Explicitly set to update.
+      // 4. The row is newer than the current highwater mark.
+      // 5. If no such property exists then try by checking the hash of the row.
+      if ($id_in_the_list || !$row->getIdMap() || $row->needsUpdate() || $this->aboveHighwater($row) || $this->rowChanged($row) ) {
+        $this->currentRow = $row->freezeSource();
+      }
+    }
+  }
+
+  /**
+   * Check if the incoming data is newer than what we've previously imported.
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The row we're importing.
+   *
+   * @return bool
+   *   TRUE if the highwater value in the row is greater than our current value.
+   */
+  protected function aboveHighwater(Row $row) {
+    return $this->highWaterProperty && $row->getSourceProperty($this->highWaterProperty['name']) > $this->originalHighWater;
+  }
+
+  /**
+   * Check if the incoming row has changed since our last import.
+   *
+   * @param \Drupal\migrate\Row $row
+   *   The row we're importing.
+   *
+   * @return bool
+   *   TRUE if the row has changed otherwise FALSE.
+   */
+  protected function rowChanged(Row $row) {
+    return $this->trackChanges && $row->changed();
+  }
+
+  /**
+   * Getter for currentSourceIds data member.
+   */
+  public function getCurrentIds() {
+    return $this->currentSourceIds;
+  }
+
+  /**
+   * Getter for numIgnored data member.
+   */
+  public function getIgnored() {
+    return $this->numIgnored;
+  }
+
+  /**
+   * Getter for numProcessed data member.
+   */
+  public function getProcessed() {
+    return $this->numProcessed;
+  }
+
+  /**
+   * Reset numIgnored back to 0.
+   */
+  public function resetStats() {
+    $this->numIgnored = 0;
+  }
+
+  /**
+   * Get the source count.
+   *
+   * Return a count of available source records, from the cache if appropriate.
+   * Returns -1 if the source is not countable.
+   *
+   * @param bool $refresh
+   *   Whether or not to refresh the count.
+   *
+   * @return int
+   *   The count.
+   */
+  public function count($refresh = FALSE) {
+    if ($this->skipCount) {
+      return -1;
+    }
+
+    if (!isset($this->cacheKey)) {
+      $this->cacheKey = hash('sha256', $this->getPluginId());
+    }
+
+    // If a refresh is requested, or we're not caching counts, ask the derived
+    // class to get the count from the source.
+    if ($refresh || !$this->cacheCounts) {
+      $count = $this->getIterator()->count();
+      $this->getCache()->set($this->cacheKey, $count, 'cache');
+    }
+    else {
+      // Caching is in play, first try to retrieve a cached count.
+      $cache_object = $this->getCache()->get($this->cacheKey, 'cache');
+      if (is_object($cache_object)) {
+        // Success.
+        $count = $cache_object->data;
+      }
+      else {
+        // No cached count, ask the derived class to count 'em up, and cache
+        // the result.
+        $count = $this->getIterator()->count();
+        $this->getCache()->set($this->cacheKey, $count, 'cache');
+      }
+    }
+    return $count;
+  }
+
+  /**
+   * Get the cache object.
+   *
+   * @return \Drupal\Core\Cache\CacheBackendInterface
+   *   The cache object.
+   */
+  protected function getCache() {
+    if (!isset($this->cache)) {
+      $this->cache = \Drupal::cache('migrate');
+    }
+    return $this->cache;
+  }
+
+}

core/modules/migrate/src/Plugin/migrate/source/SqlBase.php

@@ -0,0 +1,235 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Plugin\migrate\source\SqlBase.
+ */
+
+namespace Drupal\migrate\Plugin\migrate\source;
+
+use Drupal\Core\Database\Database;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Plugin\migrate\id_map\Sql;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+
+/**
+ * Sources whose data may be fetched via DBTNG.
+ *
+ * By default, an existing database connection with key 'migrate' and target
+ * 'default' is used. These may be overridden with explicit 'key' and/or
+ * 'target' configuration keys. In addition, if the configuration key 'database'
+ * is present, it is used as a database connection information array to define
+ * the connection.
+ */
+abstract class SqlBase extends SourcePluginBase {
+
+  /**
+   * @var \Drupal\Core\Database\Query\SelectInterface
+   */
+  protected $query;
+
+  /**
+   * @var \Drupal\migrate\Entity\MigrationInterface
+   */
+  protected $migration;
+
+  /**
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $database;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
+  }
+
+  /**
+   * Print the query string when the object is used a string.
+   *
+   * @return string
+   *   The query string.
+   */
+  public function __toString() {
+    return (string) $this->query;
+  }
+
+  /**
+   * Get the database connection object.
+   *
+   * @return \Drupal\Core\Database\Connection
+   *   The database connection.
+   */
+  public function getDatabase() {
+    if (!isset($this->database)) {
+      if (isset($this->configuration['target'])) {
+        $target = $this->configuration['target'];
+      }
+      else {
+        $target = 'default';
+      }
+      if (isset($this->configuration['key'])) {
+        $key = $this->configuration['key'];
+      }
+      else {
+        $key = 'migrate';
+      }
+      if (isset($this->configuration['database'])) {
+        Database::addConnectionInfo($key, $target, $this->configuration['database']);
+      }
+      $this->database = Database::getConnection($target, $key);
+    }
+    return $this->database;
+  }
+
+  /**
+   * Wrapper for database select.
+   */
+  protected function select($table, $alias = NULL, array $options = array()) {
+    $options['fetch'] = \PDO::FETCH_ASSOC;
+    return $this->getDatabase()->select($table, $alias, $options);
+  }
+
+  /**
+   * A helper for adding tags and metadata to the query.
+   *
+   * @return \Drupal\Core\Database\Query\SelectInterface
+   *   The query with additional tags and metadata.
+   */
+  protected function prepareQuery() {
+    $this->query = clone $this->query();
+    $this->query->addTag('migrate');
+    $this->query->addTag('migrate_' . $this->migration->id());
+    $this->query->addMetaData('migration', $this->migration);
+
+    return $this->query;
+  }
+
+  /**
+   * Implementation of MigrateSource::performRewind().
+   *
+   * We could simply execute the query and be functionally correct, but
+   * we will take advantage of the PDO-based API to optimize the query up-front.
+   */
+  protected function initializeIterator() {
+    $this->prepareQuery();
+    $high_water_property = $this->migration->get('highWaterProperty');
+
+    // Get the key values, for potential use in joining to the map table, or
+    // enforcing idlist.
+    $keys = array();
+
+    // The rules for determining what conditions to add to the query are as
+    // follows (applying first applicable rule)
+    // 1. If idlist is provided, then only process items in that list (AND key
+    //    IN (idlist)). Only applicable with single-value keys.
+    if ($id_list = $this->migration->get('idlist')) {
+      $this->query->condition($keys[0], $id_list, 'IN');
+    }
+    else {
+      // 2. If the map is joinable, join it. We will want to accept all rows
+      //    which are either not in the map, or marked in the map as NEEDS_UPDATE.
+      //    Note that if high water fields are in play, we want to accept all rows
+      //    above the high water mark in addition to those selected by the map
+      //    conditions, so we need to OR them together (but AND with any existing
+      //    conditions in the query). So, ultimately the SQL condition will look
+      //    like (original conditions) AND (map IS NULL OR map needs update
+      //      OR above high water).
+      $conditions = $this->query->orConditionGroup();
+      $condition_added = FALSE;
+      if ($this->mapJoinable()) {
+        // Build the join to the map table. Because the source key could have
+        // multiple fields, we need to build things up.
+        $count = 1;
+        $map_join = '';
+        $delimiter = '';
+        foreach ($this->getIds() as $field_name => $field_schema) {
+          if (isset($field_schema['alias'])) {
+            $field_name = $field_schema['alias'] . '.' . $field_name;
+          }
+          $map_join .= "$delimiter$field_name = map.sourceid" . $count++;
+          $delimiter = ' AND ';
+        }
+
+        $alias = $this->query->leftJoin($this->migration->getIdMap()->getQualifiedMapTableName(), 'map', $map_join);
+        $conditions->isNull($alias . '.sourceid1');
+        $conditions->condition($alias . '.source_row_status', MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
+        $condition_added = TRUE;
+
+        // And as long as we have the map table, add its data to the row.
+        $n = count($this->getIds());
+        for ($count = 1; $count <= $n; $count++) {
+          $map_key = 'sourceid' . $count;
+          $this->query->addField($alias, $map_key, "migrate_map_$map_key");
+        }
+        if ($n = count($this->migration->get('destinationIds'))) {
+          for ($count = 1; $count <= $n; $count++) {
+            $map_key = 'destid' . $count++;
+            $this->query->addField($alias, $map_key, "migrate_map_$map_key");
+          }
+        }
+        $this->query->addField($alias, 'source_row_status', 'migrate_map_source_row_status');
+      }
+      // 3. If we are using high water marks, also include rows above the mark.
+      //    But, include all rows if the high water mark is not set.
+      if (isset($high_water_property['name']) && ($high_water = $this->migration->getHighWater()) !== '') {
+        if (isset($high_water_property['alias'])) {
+          $high_water = $high_water_property['alias'] . '.' . $high_water_property['name'];
+        }
+        else {
+          $high_water = $high_water_property['name'];
+        }
+        $conditions->condition($high_water, $high_water, '>');
+        $condition_added = TRUE;
+      }
+      if ($condition_added) {
+        $this->query->condition($conditions);
+      }
+    }
+
+    return new \IteratorIterator($this->query->execute());
+  }
+
+  /**
+   * @return \Drupal\Core\Database\Query\SelectInterface
+   */
+  abstract public function query();
+
+  /**
+   * {@inheritdoc}
+   */
+  public function count() {
+    return $this->query()->countQuery()->execute()->fetchField();
+  }
+
+  /**
+   * Check if we can join against the map table.
+   *
+   * This function specifically catches issues when we're migrating with
+   * unique sets of credentials for the source and destination database.
+   *
+   * @return bool
+   *   TRUE if we can join against the map table otherwise FALSE.
+   */
+  protected function mapJoinable() {
+    if (!$this->getIds()) {
+      return FALSE;
+    }
+    $id_map = $this->migration->getIdMap();
+    if (!$id_map instanceof Sql) {
+      return FALSE;
+    }
+    $id_map_database_options = $id_map->getDatabase()->getConnectionOptions();
+    $source_database_options = $this->getDatabase()->getConnectionOptions();
+    foreach (array('username', 'password', 'host', 'port', 'namespace', 'driver') as $key) {
+      if (isset($source_database_options[$key])) {
+        if ($id_map_database_options[$key] != $source_database_options[$key]) {
+          return FALSE;
+        }
+      }
+    }
+    return TRUE;
+  }
+
+}

core/modules/migrate/src/ProcessPluginBase.php

@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\ProcessPluginBase.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\Core\Plugin\PluginBase;
+use Drupal\migrate\Plugin\MigrateProcessInterface;
+
+/**
+ * The base class for all migrate process plugins.
+ *
+ * Migrate process plugins are taking a value and transform them. For example,
+ * transform a human provided name into a machine name, look up an identifier
+ * in a previous migration and so on.
+ *
+ * @see https://www.drupal.org/node/2129651
+ * @see \Drupal\migrate\Plugin\MigratePluginManager
+ * @see \Drupal\migrate\Plugin\MigrateProcessInterface
+ * @see \Drupal\migrate\Annotation\MigrateProcessPlugin
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+abstract class ProcessPluginBase extends PluginBase implements MigrateProcessInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    // Do not call this method from children.
+    if (isset($this->configuration['method'])) {
+      if (method_exists($this, $this->configuration['method'])) {
+        return $this->{$this->configuration['method']}($value, $migrate_executable, $row, $destination_property);
+      }
+      throw new \BadMethodCallException(sprintf('The %s method does not exist in the %s plugin.', $this->configuration['method'], $this->pluginId));
+    }
+    else {
+      throw new \BadMethodCallException(sprintf('The "method" key in the plugin configuration must to be set for the %s plugin.', $this->pluginId));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function multiple() {
+    return FALSE;
+  }
+
+}

core/modules/migrate/src/Row.php

@@ -0,0 +1,323 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Row.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\Component\Utility\NestedArray;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+
+/**
+ * Stores a row.
+ */
+class Row {
+
+  /**
+   * The actual values of the source row.
+   *
+   * @var array
+   */
+  protected $source = array();
+
+  /**
+   * The source identifiers.
+   *
+   * @var array
+   */
+  protected $sourceIds = array();
+
+  /**
+   * The destination values.
+   *
+   * @var array
+   */
+  protected $destination = array();
+
+  /**
+   * Level separator of destination and source properties.
+   */
+  const PROPERTY_SEPARATOR = '/';
+
+  /**
+   * The mapping between source and destination identifiers.
+   *
+   * @var array
+   */
+  protected $idMap = array(
+    'original_hash' => '',
+    'hash' => '',
+    'source_row_status' => MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+  );
+
+  /**
+   * Whether the source has been frozen already.
+   *
+   * Once frozen the source can not be changed any more.
+   *
+   * @var bool
+   */
+  protected $frozen = FALSE;
+
+  /**
+   * The raw destination properties.
+   *
+   * Unlike $destination which is set by using
+   * \Drupal\Component\Utility\NestedArray::setValue() this array contains
+   * the destination as setDestinationProperty was called.
+   *
+   * @var array
+   *   The raw destination.
+   *
+   * @see getRawDestination()
+   */
+  protected $rawDestination;
+
+  /**
+   * TRUE when this row is a stub.
+   *
+   * @var bool
+   */
+  protected $isStub = FALSE;
+
+  /**
+   * Constructs a \Drupal\Migrate\Row object.
+   *
+   * @param array $values
+   *   An array of values to add as properties on the object.
+   * @param array $source_ids
+   *   An array containing the IDs of the source using the keys as the field
+   *   names.
+   * @param bool $is_stub
+   *   TRUE if the row being created is a stub.
+   *
+   * @throws \InvalidArgumentException
+   *   Thrown when a source ID property does not exist.
+   */
+  public function __construct(array $values, array $source_ids, $is_stub = FALSE) {
+    $this->source = $values;
+    $this->sourceIds = $source_ids;
+    $this->isStub = $is_stub;
+    foreach (array_keys($source_ids) as $id) {
+      if (!$this->hasSourceProperty($id)) {
+        throw new \InvalidArgumentException("$id has no value");
+      }
+    }
+  }
+
+  /**
+   * Retrieves the values of the source identifiers.
+   *
+   * @return array
+   *   An array containing the values of the source identifiers.
+   */
+  public function getSourceIdValues() {
+    return array_intersect_key($this->source, $this->sourceIds);
+  }
+
+  /**
+   * Determines whether a source has a property.
+   *
+   * @param string $property
+   *   A property on the source.
+   *
+   * @return bool
+   *   TRUE if the source has property; FALSE otherwise.
+   */
+  public function hasSourceProperty($property) {
+    return NestedArray::keyExists($this->source, explode(static::PROPERTY_SEPARATOR, $property));
+  }
+
+  /**
+   * Retrieves a source property.
+   *
+   * @param string $property
+   *   A property on the source.
+   *
+   * @return mixed|null
+   *   The found returned property or NULL if not found.
+   */
+  public function getSourceProperty($property) {
+    $return = NestedArray::getValue($this->source, explode(static::PROPERTY_SEPARATOR, $property), $key_exists);
+    if ($key_exists) {
+      return $return;
+    }
+  }
+
+  /**
+   * Returns the whole source array.
+   *
+   * @return array
+   *   An array of source plugins.
+   */
+  public function getSource() {
+    return $this->source;
+  }
+
+  /**
+   * Sets a source property.
+   *
+   * This can only be called from the source plugin.
+   *
+   * @param string $property
+   *   A property on the source.
+   * @param mixed $data
+   *   The property value to set on the source.
+   *
+   * @throws \Exception
+   */
+  public function setSourceProperty($property, $data) {
+    if ($this->frozen) {
+      throw new \Exception("The source is frozen and can't be changed any more");
+    }
+    else {
+      NestedArray::setValue($this->source, explode(static::PROPERTY_SEPARATOR, $property), $data, TRUE);
+    }
+  }
+
+  /**
+   * Freezes the source.
+   *
+   * @return $this
+   */
+  public function freezeSource() {
+    $this->frozen = TRUE;
+    return $this;
+  }
+
+  /**
+   * Tests if destination property exists.
+   *
+   * @param array|string $property
+   *   An array of properties on the destination.
+   *
+   * @return bool
+   *   TRUE if the destination property exists.
+   */
+  public function hasDestinationProperty($property) {
+    return NestedArray::keyExists($this->destination, explode(static::PROPERTY_SEPARATOR, $property));
+  }
+
+  /**
+   * Sets destination properties.
+   *
+   * @param string $property
+   *   The name of the destination property.
+   * @param mixed $value
+   *   The property value to set on the destination.
+   */
+  public function setDestinationProperty($property, $value) {
+    $this->rawDestination[$property] = $value;
+    NestedArray::setValue($this->destination, explode(static::PROPERTY_SEPARATOR, $property), $value, TRUE);
+  }
+
+  /**
+   * Returns the whole destination array.
+   *
+   * @return array
+   *   An array of destination values.
+   */
+  public function getDestination() {
+    return $this->destination;
+  }
+
+  /**
+   * Returns the raw destination. Rarely necessary.
+   *
+   * For example calling setDestination('foo/bar', 'baz') results in
+   * @code
+   * $this->destination['foo']['bar'] = 'baz';
+   * $this->rawDestination['foo/bar'] = 'baz';
+   * @endcode
+   *
+   * @return array
+   *   The raw destination values.
+   */
+  public function getRawDestination() {
+    return $this->rawDestination;
+  }
+
+  /**
+   * Returns the value of a destination property.
+   *
+   * @param string $property
+   *   The name of a property on the destination.
+   *
+   * @return mixed
+   *   The destination value.
+   */
+  public function getDestinationProperty($property) {
+    return NestedArray::getValue($this->destination, explode(static::PROPERTY_SEPARATOR, $property));
+  }
+
+  /**
+   * Sets the Migrate ID mappings.
+   *
+   * @param array $id_map
+   *   An array of mappings between source ID and destination ID.
+   */
+  public function setIdMap(array $id_map) {
+    $this->idMap = $id_map;
+  }
+
+  /**
+   * Retrieves the Migrate ID mappings.
+   *
+   * @return array
+   *   An array of mapping between source and destination identifiers.
+   */
+  public function getIdMap() {
+    return $this->idMap;
+  }
+
+  /**
+   * Recalculates the hash for the row.
+   */
+  public function rehash() {
+    $this->idMap['original_hash'] = $this->idMap['hash'];
+    $this->idMap['hash'] = hash('sha256', serialize($this->source));
+  }
+
+  /**
+   * Checks whether the row has changed compared to the original ID map.
+   *
+   * @return bool
+   *   TRUE if the row has changed, FALSE otherwise. If setIdMap() was not
+   *   called, this always returns FALSE.
+   */
+  public function changed() {
+    return $this->idMap['original_hash'] != $this->idMap['hash'];
+  }
+
+  /**
+   * Returns if this row needs an update.
+   *
+   * @return bool
+   *   TRUE if the row needs updating, FALSE otherwise.
+   */
+  public function needsUpdate() {
+    return $this->idMap['source_row_status'] == MigrateIdMapInterface::STATUS_NEEDS_UPDATE;
+  }
+
+  /**
+   * Returns the hash for the source values..
+   *
+   * @return mixed
+   *   The hash of the source values.
+   */
+  public function getHash() {
+    return $this->idMap['hash'];
+  }
+
+  /**
+   * Reports whether this row is a stub.
+   *
+   * @return bool
+   *   The current stub value.
+   */
+  public function isStub() {
+    return $this->isStub;
+  }
+}

core/modules/migrate/src/Tests/EntityFileTest.php

@@ -0,0 +1,295 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Tests\EntityFileTest.
+ */
+
+namespace Drupal\migrate\Tests;
+
+use Drupal\Core\Site\Settings;
+use Drupal\migrate\Row;
+use Drupal\migrate\Plugin\migrate\destination\EntityFile;
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\entity_test\Entity\EntityTest;
+use Drupal\migrate\MigrateException;
+use Drupal\simpletest\KernelTestBase;
+
+/**
+ * Tests the entity file destination plugin.
+ *
+ * @group migrate
+ */
+class EntityFileTest extends KernelTestBase {
+
+  /**
+   * Modules to install.
+   *
+   * @var array
+   */
+  public static $modules = array('system', 'entity_test', 'user', 'file');
+
+  /**
+   * @var \Drupal\migrate\Tests\TestEntityFile $destination
+   */
+  protected $destination;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+    $this->destination = new TestEntityFile([]);
+    $this->destination->streamWrapperManager = \Drupal::getContainer()->get('stream_wrapper_manager');
+    $this->destination->fileSystem = \Drupal::getContainer()->get('file_system');
+    $this->installEntitySchema('file');
+
+    file_put_contents('/tmp/test-file.jpg', '');
+  }
+
+  /**
+   * Test successful imports/copies.
+   */
+  public function testSuccessfulCopies() {
+    foreach ($this->localFileDataProvider() as $data) {
+      list($row_values, $destination_path, $expected, $source_base_path) = $data;
+
+      $this->doImport($row_values, $destination_path, $source_base_path);
+      $message = $expected ? sprintf('File %s exists', $destination_path) : sprintf('File %s does not exist', $destination_path);
+      $this->assertIdentical($expected, is_file($destination_path), $message);
+    }
+  }
+
+  /**
+   * The data provider for testing the file destination.
+   *
+   * @return array
+   *   An array of file permutations to test.
+   */
+  protected function localFileDataProvider() {
+    global $base_url;
+    return [
+      // Test a local to local copy.
+      [['filepath' => 'core/modules/simpletest/files/image-test.jpg'], 'public://file1.jpg', TRUE, DRUPAL_ROOT . '/'],
+      // Test a temporary file using an absolute path.
+      [['filepath' => '/tmp/test-file.jpg'], 'temporary://test.jpg', TRUE, ''],
+      // Test a temporary file using a relative path.
+      [['filepath' => 'test-file.jpg'], 'temporary://core/modules/simpletest/files/test.jpg', TRUE, '/tmp/'],
+      // Test a remote path to local.
+      [['filepath' => 'core/modules/simpletest/files/image-test.jpg'], 'public://remote-file.jpg', TRUE, $base_url . '/'],
+      // Test a remote path to local inside a folder that doesn't exist.
+      [['filepath' => 'core/modules/simpletest/files/image-test.jpg'], 'public://folder/remote-file.jpg', TRUE, DRUPAL_ROOT . '/'],
+    ];
+  }
+
+  /**
+   * Test that non-existent files throw an exception.
+   */
+  public function testNonExistentSourceFile() {
+    $destination = '/non/existent/file';
+    try {
+      // If this test passes, doImport() will raise a MigrateException and
+      // we'll never reach fail().
+      $this->doImport(['filepath' => $destination], 'public://wontmatter.jpg');
+      $this->fail('Expected Drupal\migrate\MigrateException when importing ' . $destination);
+    }
+    catch (MigrateException $e) {
+      $this->assertIdentical($e->getMessage(), 'File ' . $destination . ' does not exist.');
+    }
+  }
+
+  /**
+   * Tests various invocations of the writeFile() method.
+   */
+  public function testWriteFile() {
+    $plugin = $this->destination;
+    $method = new \ReflectionMethod($plugin, 'writeFile');
+    $method->setAccessible(TRUE);
+
+    touch('temporary://baz.txt');
+
+    // Moving an actual file should return TRUE.
+    $plugin->configuration['move'] = TRUE;
+    $this->assertTrue($method->invoke($plugin, 'temporary://baz.txt', 'public://foo.txt'));
+
+    // Trying to move a non-existent file should return FALSE.
+    $this->assertFalse($method->invoke($plugin, 'temporary://invalid.txt', 'public://invalid.txt'));
+
+    // Copying over a file that already exists should replace the existing file.
+    $plugin->configuration['move'] = FALSE;
+    touch('temporary://baz.txt');
+    $this->assertTrue($method->invoke($plugin, 'temporary://baz.txt', 'public://foo.txt'));
+    // Copying over a file that already exists should rename the resulting file
+    // if FILE_EXISTS_RENAME is specified.
+    $method->invoke($plugin, 'temporary://baz.txt', 'public://foo.txt', FILE_EXISTS_RENAME);
+    $this->assertTrue(file_exists('public://foo_0.txt'));
+
+    // Trying to copy a non-existent file should return FALSE.
+    $this->assertFalse($method->invoke($plugin, 'temporary://invalid.txt', 'public://invalid.txt'));
+  }
+
+  /**
+   * Tests various invocations of the getOverwriteMode() method.
+   */
+  public function testGetOverwriteMode() {
+    $plugin = $this->destination;
+    $method = new \ReflectionMethod($plugin, 'getOverwriteMode');
+    $method->setAccessible(TRUE);
+
+    $row = new Row([], []);
+    // If the plugin is not configured to rename the destination file, we should
+    // always get FILE_EXISTS_REPLACE.
+    $this->assertIdentical(FILE_EXISTS_REPLACE, $method->invoke($plugin, $row));
+
+    // When the plugin IS configured to rename the destination file, it should
+    // return FILE_EXISTS_RENAME if the destination entity already exists,
+    // and FILE_EXISTS_REPLACE otherwise.
+    $plugin->configuration['rename'] = TRUE;
+    $plugin->storage = \Drupal::entityManager()->getStorage('file');
+    /** @var \Drupal\file\FileInterface $file */
+    $file = $plugin->storage->create();
+    touch('public://foo.txt');
+    $file->setFileUri('public://foo.txt');
+    $file->save();
+    $row->setDestinationProperty($plugin->storage->getEntityType()->getKey('id'), $file->id());
+    $this->assertIdentical(FILE_EXISTS_RENAME, $method->invoke($plugin, $row));
+    unlink('public://foo.txt');
+  }
+
+  /**
+   * Tests various invocations of the getDirectory() method.
+   */
+  public function testGetDirectory() {
+    $plugin = $this->destination;
+    $method = new \ReflectionMethod($plugin, 'getDirectory');
+    $method->setAccessible(TRUE);
+
+    $this->assertEqual('public://foo', $method->invoke($plugin, 'public://foo/baz.txt'));
+    $this->assertEqual('/path/to', $method->invoke($plugin, '/path/to/foo.txt'));
+    // A directory like public:// (no path) needs to resolve to a physical path.
+    $fs = \Drupal::getContainer()->get('file_system');
+    $this->assertEqual($fs->realpath(Settings::get('file_public_path')), $method->invoke($plugin, 'public://foo.txt'));
+  }
+
+  /**
+   * Tests various invocations of the isLocationUnchanged() method.
+   */
+  public function testIsLocationUnchanged() {
+    $plugin = $this->destination;
+    $method = new \ReflectionMethod($plugin, 'isLocationUnchanged');
+    $method->setAccessible(TRUE);
+
+    $public_dir = Settings::get('file_public_path');
+
+    // Due to the limitations of realpath(), the source file must exist.
+    touch('public://foo.txt');
+    $this->assertTrue($method->invoke($plugin, $public_dir . '/foo.txt', 'public://foo.txt'));
+    unlink('public://foo.txt');
+
+    $temporary_file = '/tmp/foo.txt';
+    touch($temporary_file);
+    $this->assertTrue($method->invoke($plugin, $temporary_file, 'temporary://foo.txt'));
+    unlink($temporary_file);
+  }
+
+  /**
+   * Tests various invocations of the isLocalUri() method.
+   */
+  public function testIsLocalUri() {
+    $plugin = $this->destination;
+    $method = new \ReflectionMethod($plugin, 'isLocalUri');
+    $method->setAccessible(TRUE);
+
+    $this->assertTrue($method->invoke($plugin, 'public://foo.txt'));
+    $this->assertTrue($method->invoke($plugin, 'public://path/to/foo.txt'));
+    $this->assertTrue($method->invoke($plugin, 'temporary://foo.txt'));
+    $this->assertTrue($method->invoke($plugin, 'temporary://path/to/foo.txt'));
+    $this->assertTrue($method->invoke($plugin, 'foo.txt'));
+    $this->assertTrue($method->invoke($plugin, '/path/to/files/foo.txt'));
+    $this->assertTrue($method->invoke($plugin, 'relative/path/to/foo.txt'));
+    $this->assertFalse($method->invoke($plugin, 'http://www.example.com/foo.txt'));
+  }
+
+  /**
+   * Do an import using the destination.
+   *
+   * @param array $row_values
+   *   An array of row values.
+   * @param string $destination_path
+   *   The destination path to copy to.
+   * @param string $source_base_path
+   *   The source base path.
+   * @return array
+   *   An array of saved entities ids.
+   *
+   * @throws \Drupal\migrate\MigrateException
+   */
+  protected function doImport($row_values, $destination_path, $source_base_path = '') {
+    $row = new Row($row_values, []);
+    $row->setDestinationProperty('uri', $destination_path);
+    $this->destination->configuration['source_base_path'] = $source_base_path;
+
+    // Importing asserts there are no errors, then we just check the file has
+    // been copied into place.
+    return $this->destination->import($row, array());
+  }
+
+}
+
+class TestEntityFile extends EntityFile {
+
+  /**
+   * This is needed to be passed to $this->save().
+   *
+   * @var \Drupal\Core\Entity\ContentEntityInterface
+   */
+  public $mockEntity;
+
+  /**
+   * Make this public for easy writing during tests.
+   *
+   * @var array
+   */
+  public $configuration;
+
+  /**
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  public $storage;
+
+  /**
+   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
+   */
+  public $streamWrapperManager;
+
+  /**
+   * @var \Drupal\Core\File\FileSystemInterface
+   */
+  public $fileSystem;
+
+  public function __construct($configuration) {
+    $configuration +=  array(
+      'source_base_path' => '',
+      'source_path_property' => 'filepath',
+      'destination_path_property' => 'uri',
+      'move' => FALSE,
+      'urlencode' => FALSE,
+    );
+    $this->configuration = $configuration;
+    // We need a mock entity to be passed to save to prevent strict exceptions.
+    $this->mockEntity = EntityTest::create();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEntity(Row $row, array $old_destination_id_values) {
+    return $this->mockEntity;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function save(ContentEntityInterface $entity, array $old_destination_id_values = array()) {}
+
+}

core/modules/migrate/src/Tests/MigrateDumpAlterInterface.php

@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Tests\MigrateDumpAlterInterface.
+ */
+
+namespace Drupal\migrate\Tests;
+
+use Drupal\simpletest\TestBase;
+
+/**
+ * Allows tests to alter dumps after they've loaded.
+ *
+ * @s
+ * @see \Drupal\migrate_drupal\Tests\d6\MigrateFileTest
+ */
+interface MigrateDumpAlterInterface {
+
+  /**
+   * Allows tests to alter dumps after they've loaded.
+   *
+   * @param \Drupal\simpletest\TestBase $test
+   *   The test that is being run.
+   */
+  public static function migrateDumpAlter(TestBase $test);
+
+}

core/modules/migrate/src/Tests/MigrateTestBase.php

@@ -0,0 +1,167 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Tests\MigrateTestBase.
+ */
+
+namespace Drupal\migrate\Tests;
+
+use Drupal\Core\Database\Database;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateMessageInterface;
+use Drupal\migrate\Row;
+use Drupal\simpletest\KernelTestBase;
+
+/**
+ * Base class for migration tests.
+ */
+abstract class MigrateTestBase extends KernelTestBase implements MigrateMessageInterface {
+
+  /**
+   * The file path(s) to the dumped database(s) to load into the child site.
+   *
+   * @var array
+   */
+  public $databaseDumpFiles = array();
+
+
+  /**
+   * TRUE to collect messages instead of displaying them.
+   *
+   * @var bool
+   */
+  protected $collectMessages = FALSE;
+
+  /**
+   * A two dimensional array of messages.
+   *
+   * The first key is the type of message, the second is just numeric. Values
+   * are the messages.
+   *
+   * @var array
+   */
+  protected $migrateMessages;
+
+  public static $modules = array('migrate');
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $connection_info = Database::getConnectionInfo('default');
+    foreach ($connection_info as $target => $value) {
+      $prefix = is_array($value['prefix']) ? $value['prefix']['default'] : $value['prefix'];
+      // Simpletest uses 7 character prefixes at most so this can't cause
+      // collisions.
+      $connection_info[$target]['prefix']['default'] = $prefix . '0';
+
+      // Add the original simpletest prefix so SQLite can attach its database.
+      // @see \Drupal\Core\Database\Driver\sqlite\Connection::init()
+      $connection_info[$target]['prefix'][$value['prefix']['default']] = $value['prefix']['default'];
+    }
+    Database::addConnectionInfo('migrate', 'default', $connection_info['default']);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function tearDown() {
+    Database::removeConnection('migrate');
+    parent::tearDown();
+  }
+
+  /**
+   * Prepare the migration.
+   *
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   The migration object.
+   * @param array $files
+   *   An array of files.
+   */
+  protected function prepare(MigrationInterface $migration, array $files = array()) {
+    $this->loadDumps($files);
+    if ($this instanceof MigrateDumpAlterInterface) {
+      static::migrateDumpAlter($this);
+    }
+  }
+
+  /**
+   * Load Drupal 6 database dumps to be used.
+   *
+   * @param array $files
+   *   An array of files.
+   * @param string $method
+   *   The name of the method in the dump class to use. Defaults to load.
+   */
+  protected function loadDumps($files, $method = 'load') {
+    // Load the database from the portable PHP dump.
+    // The files may be gzipped.
+    foreach ($files as $file) {
+      if (substr($file, -3) == '.gz') {
+        $file = "compress.zlib://$file";
+        require $file;
+      }
+      preg_match('/^namespace (.*);$/m', file_get_contents($file), $matches);
+      $class = $matches[1] . '\\' . basename($file, '.php');
+      (new $class(Database::getConnection('default', 'migrate')))->$method();
+    }
+  }
+
+  /**
+   * Prepare any dependent migrations.
+   *
+   * @param array $id_mappings
+   *   A list of id mappings keyed by migration ids. Each id mapping is a list
+   *   of two arrays, the first are source ids and the second are destination
+   *   ids.
+   */
+  protected function prepareMigrations(array $id_mappings) {
+    /** @var \Drupal\migrate\Entity\MigrationInterface[] $migrations */
+    $migrations = entity_load_multiple('migration', array_keys($id_mappings));
+    foreach ($id_mappings as $migration_id => $data) {
+      $migration = $migrations[$migration_id];
+
+      // Mark the dependent migrations as complete.
+      $migration->setMigrationResult(MigrationInterface::RESULT_COMPLETED);
+
+      $id_map = $migration->getIdMap();
+      $id_map->setMessage($this);
+      $source_ids = $migration->getSourcePlugin()->getIds();
+      foreach ($data as $id_mapping) {
+        $row = new Row(array_combine(array_keys($source_ids), $id_mapping[0]), $source_ids);
+        $id_map->saveIdMapping($row, $id_mapping[1]);
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function display($message, $type = 'status') {
+    if ($this->collectMessages) {
+      $this->migrateMessages[$type][] = $message;
+    }
+    else {
+      $this->assert($type == 'status', $message, 'migrate');
+    }
+  }
+
+  /**
+   * Start collecting messages and erase previous messages.
+   */
+  public function startCollectingMessages() {
+    $this->collectMessages = TRUE;
+    $this->migrateMessages = array();
+  }
+
+  /**
+   * Stop collecting messages.
+   */
+  public function stopCollectingMessages() {
+    $this->collectMessages = FALSE;
+  }
+
+}

core/modules/migrate/src/Tests/SqlBaseTest.php

@@ -0,0 +1,106 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Tests\SqlBaseTest
+ */
+
+namespace Drupal\migrate\Tests;
+
+use Drupal\migrate\Plugin\migrate\source\TestSqlBase;
+use Drupal\Core\Database\Database;
+
+/**
+ * Test the functionality of SqlBase.
+ *
+ * @group migrate
+ */
+class SqlBaseTest extends MigrateTestBase {
+
+  /**
+   * Test different connection types.
+   */
+  public function testConnectionTypes() {
+    $sql_base = new TestSqlBase();
+
+    // Check the default values.
+    $this->assertIdentical($sql_base->getDatabase()->getTarget(), 'default');
+    $this->assertIdentical($sql_base->getDatabase()->getKey(), 'migrate');
+
+    $target = 'test_db_target';
+    $key = 'test_migrate_connection';
+    $config = array('target' => $target, 'key' => $key);
+    $sql_base->setConfiguration($config);
+    Database::addConnectionInfo($key, $target, Database::getConnectionInfo('default')['default']);
+
+    // Validate we've injected our custom key and target.
+    $this->assertIdentical($sql_base->getDatabase()->getTarget(), $target);
+    $this->assertIdentical($sql_base->getDatabase()->getKey(), $key);
+
+    // Now test we can have SqlBase create the connection from an info array.
+    $sql_base = new TestSqlBase();
+
+    $target = 'test_db_target2';
+    $key = 'test_migrate_connection2';
+    $database = Database::getConnectionInfo('default')['default'];
+    $config = array('target' => $target, 'key' => $key, 'database' => $database);
+    $sql_base->setConfiguration($config);
+
+    // Call getDatabase() to get the connection defined.
+    $sql_base->getDatabase();
+
+    // Validate the connection has been created with the right values.
+    $this->assertIdentical(Database::getConnectionInfo($key)[$target], $database);
+
+  }
+
+}
+
+namespace Drupal\migrate\Plugin\migrate\source;
+
+/**
+ * A dummy source to help with testing SqlBase.
+ *
+ * @package Drupal\migrate\Plugin\migrate\source
+ */
+class TestSqlBase extends SqlBase {
+
+  /**
+   * Override the constructor so we can create one easily.
+   */
+  public function __construct() {}
+
+  /**
+   * Get the database without caching it.
+   */
+  public function getDatabase() {
+    $this->database = NULL;
+    return parent::getDatabase();
+  }
+
+  /**
+   * Allow us to set the configuration from a test.
+   *
+   * @param array $config
+   *   The config array.
+   */
+  public function setConfiguration($config) {
+    $this->configuration = $config;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields() {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function query() {}
+
+}

core/modules/migrate/tests/src/Unit/Entity/MigrationTest.php

@@ -0,0 +1,31 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\Entity\MigrationTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit\Entity;
+
+use Drupal\migrate\Entity\Migration;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Tests the migrate entity.
+ *
+ * @coversDefaultClass \Drupal\migrate\Entity\Migration
+ * @group migrate
+ */
+class MigrationTest extends UnitTestCase {
+
+  /**
+   * Tests Migration::getProcessPlugins()
+   *
+   * @covers ::getProcessPlugins
+   */
+  public function testGetProcessPlugins() {
+    $migration = new Migration([], 'migration');
+    $this->assertEquals([], $migration->getProcessPlugins([]));
+  }
+
+}

core/modules/migrate/tests/src/Unit/MigrateExecutableMemoryExceededTest.php

@@ -0,0 +1,120 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\MigrateExecutableMemoryExceededTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+/**
+ * Tests the \Drupal\migrate\MigrateExecutable::memoryExceeded() method.
+ *
+ * @group migrate
+ */
+class MigrateExecutableMemoryExceededTest extends MigrateTestCase {
+
+  /**
+   * The mocked migration entity.
+   *
+   * @var \Drupal\migrate\Entity\MigrationInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $migration;
+
+  /**
+   * The mocked migrate message.
+   *
+   * @var \Drupal\migrate\MigrateMessageInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $message;
+
+  /**
+   * The tested migrate executable.
+   *
+   * @var \Drupal\Tests\migrate\Unit\TestMigrateExecutable
+   */
+  protected $executable;
+
+  /**
+   * The migration configuration, initialized to set the ID to test.
+   *
+   * @var array
+   */
+  protected $migrationConfiguration = array(
+    'id' => 'test',
+  );
+
+  /**
+   * php.init memory_limit value.
+   */
+  protected $memoryLimit = 10000000;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->migration = $this->getMigration();
+    $this->message = $this->getMock('Drupal\migrate\MigrateMessageInterface');
+
+    $this->executable = new TestMigrateExecutable($this->migration, $this->message);
+    $this->executable->setStringTranslation($this->getStringTranslationStub());
+  }
+
+  /**
+   * Runs the actual test.
+   *
+   * @param string $message
+   *   The second message to assert.
+   * @param bool $memory_exceeded
+   *   Whether to test the memory exceeded case.
+   * @param int $memory_usage_first
+   *   (optional) The first memory usage value.
+   * @param int $memory_usage_second
+   *   (optional) The fake amount of memory usage reported after memory reclaim.
+   * @param int $memory_limit
+   *   (optional) The memory limit.
+   */
+  protected function runMemoryExceededTest($message, $memory_exceeded, $memory_usage_first = NULL, $memory_usage_second = NULL, $memory_limit = NULL) {
+    $this->executable->setMemoryLimit($memory_limit ?: $this->memoryLimit);
+    $this->executable->setMemoryUsage($memory_usage_first ?: $this->memoryLimit, $memory_usage_second ?: $this->memoryLimit);
+    $this->executable->setMemoryThreshold(0.85);
+    if ($message) {
+      $this->executable->message->expects($this->at(0))
+        ->method('display')
+        ->with($this->stringContains('reclaiming memory'));
+      $this->executable->message->expects($this->at(1))
+        ->method('display')
+        ->with($this->stringContains($message));
+    }
+    else {
+      $this->executable->message->expects($this->never())
+        ->method($this->anything());
+    }
+    $result = $this->executable->memoryExceeded();
+    $this->assertEquals($memory_exceeded, $result);
+  }
+
+  /**
+   * Tests memoryExceeded method when a new batch is needed.
+   */
+  public function testMemoryExceededNewBatch() {
+    // First case try reset and then start new batch.
+    $this->runMemoryExceededTest('starting new batch', TRUE);
+  }
+
+  /**
+   * Tests memoryExceeded method when enough is cleared.
+   */
+  public function testMemoryExceededClearedEnough() {
+    $this->runMemoryExceededTest('reclaimed enough', FALSE, $this->memoryLimit, $this->memoryLimit * 0.75);
+  }
+
+  /**
+   * Tests memoryExceeded when memory usage is not exceeded.
+   */
+  public function testMemoryNotExceeded() {
+    $this->runMemoryExceededTest('', FALSE, floor($this->memoryLimit * 0.85) - 1);
+  }
+
+}

core/modules/migrate/tests/src/Unit/MigrateExecutableTest.php

@@ -0,0 +1,525 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\MigrateExecutableTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\Row;
+
+/**
+ * @coversDefaultClass \Drupal\Tests\migrate\Unit\MigrateExecutableTest
+ * @group migrate
+ */
+class MigrateExecutableTest extends MigrateTestCase {
+
+  /**
+   * The mocked migration entity.
+   *
+   * @var \Drupal\migrate\Entity\MigrationInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $migration;
+
+  /**
+   * The mocked migrate message.
+   *
+   * @var \Drupal\migrate\MigrateMessageInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $message;
+
+  /**
+   * The tested migrate executable.
+   *
+   * @var \Drupal\Tests\migrate\Unit\TestMigrateExecutable
+   */
+  protected $executable;
+
+  protected $migrationConfiguration = array(
+    'id' => 'test',
+  );
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->migration = $this->getMigration();
+    $this->message = $this->getMock('Drupal\migrate\MigrateMessageInterface');
+
+    $this->executable = new TestMigrateExecutable($this->migration, $this->message);
+    $this->executable->setStringTranslation($this->getStringTranslationStub());
+    $this->executable->setTimeThreshold(0.1);
+    $this->executable->limit = array('unit' => 'second', 'value' => 1);
+  }
+
+  /**
+   * Tests an import with an incomplete rewinding.
+   */
+  public function testImportWithFailingRewind() {
+    $exception_message = $this->getRandomGenerator()->string();
+    $source = $this->getMock('Drupal\migrate\Plugin\MigrateSourceInterface');
+    $source->expects($this->once())
+      ->method('rewind')
+      ->will($this->throwException(new \Exception($exception_message)));
+
+    $this->migration->expects($this->any())
+      ->method('getSourcePlugin')
+      ->will($this->returnValue($source));
+
+    // Ensure that a message with the proper message was added.
+    $this->message->expects($this->once())
+      ->method('display')
+      ->with("Migration failed with source plugin exception: $exception_message");
+
+    $result = $this->executable->import();
+    $this->assertEquals(MigrationInterface::RESULT_FAILED, $result);
+  }
+
+  /**
+   * Tests the import method with a valid row.
+   */
+  public function testImportWithValidRow() {
+    $source = $this->getMockSource();
+
+    $row = $this->getMockBuilder('Drupal\migrate\Row')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $row->expects($this->once())
+      ->method('getSourceIdValues')
+      ->will($this->returnValue(array('id' => 'test')));
+
+    $this->idMap->expects($this->once())
+      ->method('lookupDestinationId')
+      ->with(array('id' => 'test'))
+      ->will($this->returnValue(array('test')));
+
+    $source->expects($this->once())
+      ->method('current')
+      ->will($this->returnValue($row));
+
+    $this->executable->setSource($source);
+
+    $this->migration->expects($this->once())
+      ->method('getProcessPlugins')
+      ->will($this->returnValue(array()));
+
+    $destination = $this->getMock('Drupal\migrate\Plugin\MigrateDestinationInterface');
+    $destination->expects($this->once())
+      ->method('import')
+      ->with($row, array('test'))
+      ->will($this->returnValue(array('id' => 'test')));
+
+    $this->migration->expects($this->once())
+      ->method('getDestinationPlugin')
+      ->will($this->returnValue($destination));
+
+    $this->assertSame(MigrationInterface::RESULT_COMPLETED, $this->executable->import());
+
+    $this->assertSame(1, $this->executable->getSuccessesSinceFeedback());
+    $this->assertSame(1, $this->executable->getTotalSuccesses());
+    $this->assertSame(1, $this->executable->getTotalProcessed());
+    $this->assertSame(1, $this->executable->getProcessedSinceFeedback());
+  }
+
+  /**
+   * Tests the import method with a valid row.
+   */
+  public function testImportWithValidRowWithoutDestinationId() {
+    $source = $this->getMockSource();
+
+    $row = $this->getMockBuilder('Drupal\migrate\Row')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $row->expects($this->once())
+      ->method('getSourceIdValues')
+      ->will($this->returnValue(array('id' => 'test')));
+
+    $this->idMap->expects($this->once())
+      ->method('lookupDestinationId')
+      ->with(array('id' => 'test'))
+      ->will($this->returnValue(array('test')));
+
+    $source->expects($this->once())
+      ->method('current')
+      ->will($this->returnValue($row));
+
+    $this->executable->setSource($source);
+
+    $this->migration->expects($this->once())
+      ->method('getProcessPlugins')
+      ->will($this->returnValue(array()));
+
+    $destination = $this->getMock('Drupal\migrate\Plugin\MigrateDestinationInterface');
+    $destination->expects($this->once())
+      ->method('import')
+      ->with($row, array('test'))
+      ->will($this->returnValue(TRUE));
+
+    $this->migration->expects($this->once())
+      ->method('getDestinationPlugin')
+      ->will($this->returnValue($destination));
+
+    $this->idMap->expects($this->never())
+      ->method('saveIdMapping');
+
+    $this->assertSame(MigrationInterface::RESULT_COMPLETED, $this->executable->import());
+
+    $this->assertSame(1, $this->executable->getSuccessesSinceFeedback());
+    $this->assertSame(1, $this->executable->getTotalSuccesses());
+    $this->assertSame(1, $this->executable->getTotalProcessed());
+    $this->assertSame(1, $this->executable->getProcessedSinceFeedback());
+  }
+
+  /**
+   * Tests the import method with a valid row.
+   */
+  public function testImportWithValidRowNoDestinationValues() {
+    $source = $this->getMockSource();
+
+    $row = $this->getMockBuilder('Drupal\migrate\Row')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $row->expects($this->once())
+      ->method('getSourceIdValues')
+      ->will($this->returnValue(array('id' => 'test')));
+
+    $source->expects($this->once())
+      ->method('current')
+      ->will($this->returnValue($row));
+
+    $this->executable->setSource($source);
+
+    $this->migration->expects($this->once())
+      ->method('getProcessPlugins')
+      ->will($this->returnValue(array()));
+
+    $destination = $this->getMock('Drupal\migrate\Plugin\MigrateDestinationInterface');
+    $destination->expects($this->once())
+      ->method('import')
+      ->with($row, array('test'))
+      ->will($this->returnValue(array()));
+
+    $this->migration->expects($this->once())
+      ->method('getDestinationPlugin')
+      ->will($this->returnValue($destination));
+
+    $this->idMap->expects($this->once())
+      ->method('delete')
+      ->with(array('id' => 'test'), TRUE);
+
+    $this->idMap->expects($this->once())
+      ->method('saveIdMapping')
+      ->with($row, array(), MigrateIdMapInterface::STATUS_FAILED, NULL);
+
+    $this->idMap->expects($this->once())
+      ->method('messageCount')
+      ->will($this->returnValue(0));
+
+    $this->idMap->expects($this->once())
+      ->method('saveMessage');
+
+    $this->idMap->expects($this->once())
+      ->method('lookupDestinationId')
+      ->with(array('id' => 'test'))
+      ->will($this->returnValue(array('test')));
+
+    $this->message->expects($this->once())
+      ->method('display')
+      ->with('New object was not saved, no error provided');
+
+    $this->assertSame(MigrationInterface::RESULT_COMPLETED, $this->executable->import());
+  }
+
+  /**
+   * Tests the import method with a MigrateException being thrown.
+   */
+  public function testImportWithValidRowWithMigrateException() {
+    $exception_message = $this->getRandomGenerator()->string();
+    $source = $this->getMockSource();
+
+    $row = $this->getMockBuilder('Drupal\migrate\Row')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $row->expects($this->once())
+      ->method('getSourceIdValues')
+      ->will($this->returnValue(array('id' => 'test')));
+
+    $source->expects($this->once())
+      ->method('current')
+      ->will($this->returnValue($row));
+
+    $this->executable->setSource($source);
+
+    $this->migration->expects($this->once())
+      ->method('getProcessPlugins')
+      ->will($this->returnValue(array()));
+
+    $destination = $this->getMock('Drupal\migrate\Plugin\MigrateDestinationInterface');
+    $destination->expects($this->once())
+      ->method('import')
+      ->with($row, array('test'))
+      ->will($this->throwException(new MigrateException($exception_message)));
+
+    $this->migration->expects($this->once())
+      ->method('getDestinationPlugin')
+      ->will($this->returnValue($destination));
+
+    $this->idMap->expects($this->once())
+      ->method('saveIdMapping')
+      ->with($row, array(), MigrateIdMapInterface::STATUS_FAILED, NULL);
+
+    $this->idMap->expects($this->once())
+      ->method('saveMessage');
+
+    $this->message->expects($this->once())
+      ->method('display')
+      ->with($exception_message);
+
+    $this->idMap->expects($this->once())
+      ->method('lookupDestinationId')
+      ->with(array('id' => 'test'))
+      ->will($this->returnValue(array('test')));
+
+    $this->assertSame(MigrationInterface::RESULT_COMPLETED, $this->executable->import());
+  }
+
+  /**
+   * Tests the import method with a regular Exception being thrown.
+   */
+  public function testImportWithValidRowWithException() {
+    $exception_message = $this->getRandomGenerator()->string();
+    $source = $this->getMockSource();
+
+    $row = $this->getMockBuilder('Drupal\migrate\Row')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $row->expects($this->once())
+      ->method('getSourceIdValues')
+      ->will($this->returnValue(array('id' => 'test')));
+
+    $source->expects($this->once())
+      ->method('current')
+      ->will($this->returnValue($row));
+
+    $this->executable->setSource($source);
+
+    $this->migration->expects($this->once())
+      ->method('getProcessPlugins')
+      ->will($this->returnValue(array()));
+
+    $destination = $this->getMock('Drupal\migrate\Plugin\MigrateDestinationInterface');
+    $destination->expects($this->once())
+      ->method('import')
+      ->with($row, array('test'))
+      ->will($this->throwException(new \Exception($exception_message)));
+
+    $this->migration->expects($this->once())
+      ->method('getDestinationPlugin')
+      ->will($this->returnValue($destination));
+
+    $this->idMap->expects($this->once())
+      ->method('saveIdMapping')
+      ->with($row, array(), MigrateIdMapInterface::STATUS_FAILED, NULL);
+
+    $this->idMap->expects($this->once())
+      ->method('saveMessage');
+
+    $this->idMap->expects($this->once())
+      ->method('lookupDestinationId')
+      ->with(array('id' => 'test'))
+      ->will($this->returnValue(array('test')));
+
+    $this->message->expects($this->once())
+      ->method('display')
+      ->with($exception_message);
+
+    $this->assertSame(MigrationInterface::RESULT_COMPLETED, $this->executable->import());
+  }
+
+  /**
+   * Tests time limit option method.
+   */
+  public function testTimeOptionExceeded() {
+    // Assert time limit of one second (test configuration default) is exceeded.
+    $this->executable->setTimeElapsed(1);
+    $this->assertTrue($this->executable->timeOptionExceeded());
+    // Assert time limit not exceeded.
+    $this->executable->limit = array('unit' => 'seconds', 'value' => (int) $_SERVER['REQUEST_TIME'] - 3600);
+    $this->assertFalse($this->executable->timeOptionExceeded());
+    // Assert no time limit.
+    $this->executable->limit = array();
+    $this->assertFalse($this->executable->timeOptionExceeded());
+  }
+
+  /**
+   * Tests get time limit method.
+   */
+  public function testGetTimeLimit() {
+    // Assert time limit has a unit of one second (test configuration default).
+    $limit = $this->executable->limit;
+    $this->assertArrayHasKey('unit', $limit);
+    $this->assertSame('second', $limit['unit']);
+    $this->assertSame($limit['value'], $this->executable->getTimeLimit());
+    // Assert time limit has a unit of multiple seconds.
+    $this->executable->limit = array('unit' => 'seconds', 'value' => 30);
+    $limit = $this->executable->limit;
+    $this->assertArrayHasKey('unit', $limit);
+    $this->assertSame('seconds', $limit['unit']);
+    $this->assertSame($limit['value'], $this->executable->getTimeLimit());
+    // Assert no time limit.
+    $this->executable->limit = array();
+    $limit = $this->executable->limit;
+    $this->assertArrayNotHasKey('unit', $limit);
+    $this->assertArrayNotHasKey('value', $limit);
+    $this->assertNull($this->executable->getTimeLimit());
+  }
+
+  /**
+   * Tests saving of queued messages.
+   */
+  public function testSaveQueuedMessages() {
+    // Assert no queued messages before save.
+    $this->assertAttributeEquals(array(), 'queuedMessages', $this->executable);
+    // Set required source_id_values for MigrateIdMapInterface::saveMessage().
+    $expected_messages[] = array('message' => 'message 1', 'level' => MigrationInterface::MESSAGE_ERROR);
+    $expected_messages[] = array('message' => 'message 2', 'level' => MigrationInterface::MESSAGE_WARNING);
+    $expected_messages[] = array('message' => 'message 3', 'level' => MigrationInterface::MESSAGE_INFORMATIONAL);
+    foreach ($expected_messages as $queued_message) {
+      $this->executable->queueMessage($queued_message['message'], $queued_message['level']);
+    }
+    $this->executable->setSourceIdValues(array());
+    $this->assertAttributeEquals($expected_messages, 'queuedMessages', $this->executable);
+    // No asserts of saved messages since coverage exists
+    // in MigrateSqlIdMapTest::saveMessage().
+    $this->executable->saveQueuedMessages();
+    // Assert no queued messages after save.
+    $this->assertAttributeEquals(array(), 'queuedMessages', $this->executable);
+  }
+
+  /**
+   * Tests the queuing of messages.
+   */
+  public function testQueueMessage() {
+    // Assert no queued messages.
+    $expected_messages = array();
+    $this->assertAttributeEquals(array(), 'queuedMessages', $this->executable);
+    // Assert a single (default level) queued message.
+    $expected_messages[] = array(
+      'message' => 'message 1',
+      'level' => MigrationInterface::MESSAGE_ERROR,
+    );
+    $this->executable->queueMessage('message 1');
+    $this->assertAttributeEquals($expected_messages, 'queuedMessages', $this->executable);
+    // Assert multiple queued messages.
+    $expected_messages[] = array(
+      'message' => 'message 2',
+      'level' => MigrationInterface::MESSAGE_WARNING,
+    );
+    $this->executable->queueMessage('message 2', MigrationInterface::MESSAGE_WARNING);
+    $this->assertAttributeEquals($expected_messages, 'queuedMessages', $this->executable);
+    $expected_messages[] = array(
+      'message' => 'message 3',
+      'level' => MigrationInterface::MESSAGE_INFORMATIONAL,
+    );
+    $this->executable->queueMessage('message 3', MigrationInterface::MESSAGE_INFORMATIONAL);
+    $this->assertAttributeEquals($expected_messages, 'queuedMessages', $this->executable);
+  }
+
+  /**
+   * Tests maximum execution time (max_execution_time) of an import.
+   */
+  public function testMaxExecTimeExceeded() {
+    // Assert no max_execution_time value.
+    $this->executable->setMaxExecTime(0);
+    $this->assertFalse($this->executable->maxExecTimeExceeded());
+    // Assert default max_execution_time value does not exceed.
+    $this->executable->setMaxExecTime(30);
+    $this->assertFalse($this->executable->maxExecTimeExceeded());
+    // Assert max_execution_time value is exceeded.
+    $this->executable->setMaxExecTime(1);
+    $this->executable->setTimeElapsed(2);
+    $this->assertTrue($this->executable->maxExecTimeExceeded());
+  }
+
+  /**
+   * Tests the processRow method.
+   */
+  public function testProcessRow() {
+    $expected = array(
+      'test' => 'test destination',
+      'test1' => 'test1 destination'
+    );
+    foreach ($expected as $key => $value) {
+      $plugins[$key][0] = $this->getMock('Drupal\migrate\Plugin\MigrateProcessInterface');
+      $plugins[$key][0]->expects($this->once())
+        ->method('getPluginDefinition')
+        ->will($this->returnValue(array()));
+      $plugins[$key][0]->expects($this->once())
+        ->method('transform')
+        ->will($this->returnValue($value));
+    }
+    $this->migration->expects($this->once())
+      ->method('getProcessPlugins')
+      ->with(NULL)
+      ->will($this->returnValue($plugins));
+    $row = new Row(array(), array());
+    $this->executable->processRow($row);
+    foreach ($expected as $key => $value) {
+      $this->assertSame($row->getDestinationProperty($key), $value);
+    }
+    $this->assertSame(count($row->getDestination()), count($expected));
+  }
+
+  /**
+   * Tests the processRow method with an empty pipeline.
+   */
+  public function testProcessRowEmptyPipeline() {
+    $this->migration->expects($this->once())
+      ->method('getProcessPlugins')
+      ->with(NULL)
+      ->will($this->returnValue(array('test' => array())));
+    $row = new Row(array(), array());
+    $this->executable->processRow($row);
+    $this->assertSame($row->getDestination(), array());
+  }
+
+  /**
+   * Returns a mock migration source instance.
+   *
+   * @return \Drupal\migrate\Plugin\MigrateSourceInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected function getMockSource() {
+    $iterator = $this->getMock('\Iterator');
+
+    $class = 'Drupal\migrate\Plugin\migrate\source\SourcePluginBase';
+    $source = $this->getMockBuilder($class)
+      ->disableOriginalConstructor()
+      ->setMethods(get_class_methods($class))
+      ->getMockForAbstractClass();
+    $source->expects($this->any())
+      ->method('getIterator')
+      ->will($this->returnValue($iterator));
+    $source->expects($this->once())
+      ->method('rewind')
+      ->will($this->returnValue(TRUE));
+    $source->expects($this->any())
+      ->method('initializeIterator')
+      ->will($this->returnValue([]));
+    $source->expects($this->any())
+      ->method('valid')
+      ->will($this->onConsecutiveCalls(TRUE, FALSE));
+
+    return $source;
+  }
+
+}

core/modules/migrate/tests/src/Unit/MigrateSourceTest.php

@@ -0,0 +1,245 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\MigrateSourceTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\migrate\MigrateExecutable;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+
+/**
+ * @coversDefaultClass \Drupal\migrate\Plugin\migrate\source\SourcePluginBase
+ * @group migrate
+ */
+class MigrateSourceTest extends MigrateTestCase {
+
+  /**
+   * Override the migration config.
+   *
+   * @var array
+   */
+  protected $defaultMigrationConfiguration = [
+    'id' => 'test_migration',
+    'source' => [],
+  ];
+
+  /**
+   * Test row data.
+   *
+   * @var array
+   */
+  protected $row = ['test_sourceid1' => '1', 'timestamp' => 500];
+
+  /**
+   * Test source ids.
+   *
+   * @var array
+   */
+  protected $sourceIds = ['test_sourceid1' => 'test_sourceid1'];
+
+  /**
+   * The migration entity.
+   *
+   * @var \Drupal\migrate\Entity\Migration
+   */
+  protected $migration;
+
+  /**
+   * The migrate executable.
+   *
+   * @var \Drupal\migrate\MigrateExecutable
+   */
+  protected $executable;
+
+  /**
+   * Get the source plugin to test.
+   *
+   * @param array $configuration
+   *   The source configuration.
+   * @param array $migrate_config
+   *   The migration configuration to be used in parent::getMigration().
+   * @param int $status
+   *   The default status for the new rows to be imported.
+   *
+   * @return \Drupal\migrate\Plugin\MigrateSourceInterface
+   *   A mocked source plugin.
+   */
+  protected function getSource($configuration = [], $migrate_config = [], $status = MigrateIdMapInterface::STATUS_NEEDS_UPDATE) {
+    $this->migrationConfiguration = $this->defaultMigrationConfiguration + $migrate_config;
+    $this->migration = parent::getMigration();
+    $this->executable = $this->getMigrateExecutable($this->migration);
+
+    // Update the idMap for Source so the default is that the row has already
+    // been imported. This allows us to use the highwater mark to decide on the
+    // outcome of whether we choose to import the row.
+    $id_map_array = ['original_hash' => '', 'hash' => '', 'source_row_status' => $status];
+    $this->idMap
+      ->expects($this->any())
+      ->method('getRowBySource')
+      ->willReturn($id_map_array);
+
+    $constructor_args = [$configuration, 'd6_action', [], $this->migration];
+    $methods = ['getModuleHandler', 'fields', 'getIds', '__toString', 'getIterator', 'prepareRow', 'initializeIterator', 'calculateDependencies'];
+    $source_plugin = $this->getMock('\Drupal\migrate\Plugin\migrate\source\SourcePluginBase', $methods, $constructor_args);
+
+    $source_plugin
+      ->expects($this->any())
+      ->method('fields')
+      ->willReturn([]);
+    $source_plugin
+      ->expects($this->any())
+      ->method('getIds')
+      ->willReturn([]);
+    $source_plugin
+      ->expects($this->any())
+      ->method('__toString')
+      ->willReturn('');
+    $source_plugin
+      ->expects($this->any())
+      ->method('prepareRow')
+      ->willReturn(empty($migrate_config['prepare_row_false']));
+    $source_plugin
+      ->expects($this->any())
+      ->method('initializeIterator')
+      ->willReturn([]);
+    $iterator = new \ArrayIterator([$this->row]);
+    $source_plugin
+      ->expects($this->any())
+      ->method('getIterator')
+      ->willReturn($iterator);
+
+    $module_handler = $this->getMock('\Drupal\Core\Extension\ModuleHandlerInterface');
+    $source_plugin
+      ->expects($this->any())
+      ->method('getModuleHandler')
+      ->willReturn($module_handler);
+
+    $this->migration
+      ->expects($this->any())
+      ->method('getSourcePlugin')
+      ->willReturn($source_plugin);
+
+    return $this->migration->getSourcePlugin();
+  }
+
+  /**
+   * @expectedException \Drupal\migrate\MigrateException
+   */
+  public function testHighwaterTrackChangesIncompatible() {
+    $source_config = ['track_changes' => TRUE];
+    $migration_config = ['highWaterProperty' => ['name' => 'something']];
+    $this->getSource($source_config, $migration_config);
+  }
+
+  /**
+   * Test that the source count is correct.
+   */
+  public function testCount() {
+
+    $container = new ContainerBuilder();
+    $container->register('cache.migrate', 'Drupal\Core\Cache\NullBackend')
+      ->setArguments(['migrate']);
+    \Drupal::setContainer($container);
+
+    // Test that the basic count works.
+    $source = $this->getSource();
+    $this->assertEquals(1, $source->count());
+
+    // Test caching the count works.
+    $source = $this->getSource(['cache_counts' => TRUE]);
+    $this->assertEquals(1, $source->count());
+
+    // Test the skip argument.
+    $source = $this->getSource(['skip_count' => TRUE]);
+    $this->assertEquals(-1, $source->count());
+  }
+
+  /**
+   * Test that we don't get a row if prepareRow() is false.
+   */
+  public function testPrepareRowFalse() {
+    $source = $this->getSource([], ['prepare_row_false' => TRUE]);
+
+    $source->rewind();
+    $this->assertNull($source->current(), 'No row is available when prepareRow() is false.');
+  }
+
+  /**
+   * Test that the when a source id is in the idList, we don't get a row.
+   */
+  public function testIdInList() {
+    $source = $this->getSource([], ['idlist' => ['test_sourceid1']]);
+    $source->rewind();
+
+    $this->assertNull($source->current(), 'No row is available because id was in idList.');
+  }
+
+  /**
+   * Test that $row->needsUpdate() works as expected.
+   */
+  public function testNextNeedsUpdate() {
+    $source = $this->getSource();
+
+    // $row->needsUpdate() === TRUE so we get a row.
+    $source->rewind();
+    $this->assertTrue(is_a($source->current(), 'Drupal\migrate\Row'), '$row->needsUpdate() is TRUE so we got a row.');
+
+    // Test that we don't get a row when the incoming row is marked as imported.
+    $source = $this->getSource([], [], MigrateIdMapInterface::STATUS_IMPORTED);
+    $source->rewind();
+    $this->assertNull($source->current(), 'Row was already imported, should be NULL');
+  }
+
+  /**
+   * Test that an outdated highwater mark does not cause a row to be imported.
+   */
+  public function testOutdatedHighwater() {
+
+    $source = $this->getSource([], [], MigrateIdMapInterface::STATUS_IMPORTED);
+
+    // Set the originalHighwater to something higher than our timestamp.
+    $this->migration
+      ->expects($this->any())
+      ->method('getHighwater')
+      ->willReturn($this->row['timestamp'] + 1);
+
+    // The current highwater mark is now higher than the row timestamp so no row
+    // is expected.
+    $source->rewind();
+    $this->assertNull($source->current(), 'Original highwater mark is higher than incoming row timestamp.');
+  }
+
+  /**
+   * Test that a highwater mark newer than our saved one imports a row.
+   *
+   * @throws \Exception
+   */
+  public function testNewHighwater() {
+
+    // Set a highwater property field for source. Now we should have a row
+    // because the row timestamp is greater than the current highwater mark.
+    $source = $this->getSource([], ['highWaterProperty' => ['name' => 'timestamp']], MigrateIdMapInterface::STATUS_IMPORTED);
+
+    $source->rewind();
+    $this->assertTrue(is_a($source->current(), 'Drupal\migrate\Row'), 'Incoming row timestamp is greater than current highwater mark so we have a row.');
+  }
+
+  /**
+   * Get a mock executable for the test.
+   *
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   The migration entity.
+   *
+   * @return \Drupal\migrate\MigrateExecutable
+   *   The migrate executable.
+   */
+  protected function getMigrateExecutable($migration) {
+    $message = $this->getMock('Drupal\migrate\MigrateMessageInterface');
+    return new MigrateExecutable($migration, $message);
+  }
+
+}

core/modules/migrate/tests/src/Unit/MigrateSqlIdMapEnsureTablesTest.php

@@ -0,0 +1,212 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\MigrateSqlIdMapEnsureTablesTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+
+/**
+ * Tests the SQL ID map plugin ensureTables() method.
+ *
+ * @group migrate
+ */
+class MigrateSqlIdMapEnsureTablesTest extends MigrateTestCase {
+
+  /**
+   * The migration configuration, initialized to set the ID and destination IDs.
+   *
+   * @var array
+   */
+  protected $migrationConfiguration = array(
+    'id' => 'sql_idmap_test',
+  );
+
+  /**
+   * Tests the ensureTables method when the tables do not exist.
+   */
+  public function testEnsureTablesNotExist() {
+    $fields['source_row_status'] = array(
+      'type' => 'int',
+      'size' => 'tiny',
+      'unsigned' => TRUE,
+      'not null' => TRUE,
+      'default' => MigrateIdMapInterface::STATUS_IMPORTED,
+      'description' => 'Indicates current status of the source row',
+    );
+    $fields['rollback_action'] = array(
+      'type' => 'int',
+      'size' => 'tiny',
+      'unsigned' => TRUE,
+      'not null' => TRUE,
+      'default' => MigrateIdMapInterface::ROLLBACK_DELETE,
+      'description' => 'Flag indicating what to do for this item on rollback',
+    );
+    $fields['last_imported'] = array(
+      'type' => 'int',
+      'unsigned' => TRUE,
+      'not null' => TRUE,
+      'default' => 0,
+      'description' => 'UNIX timestamp of the last time this row was imported',
+    );
+    $fields['hash'] = array(
+      'type' => 'varchar',
+      'length' => '64',
+      'not null' => FALSE,
+      'description' => 'Hash of source row data, for detecting changes',
+    );
+    $fields['sourceid1'] = array(
+      'type' => 'int',
+      'not null' => TRUE,
+    );
+    $fields['destid1'] = array(
+      'type' => 'varchar',
+      'length' => 255,
+      'not null' => FALSE,
+    );
+    $map_table_schema = array(
+      'description' => 'Mappings from source identifier value(s) to destination identifier value(s).',
+      'fields' => $fields,
+      'primary key' => array('sourceid1'),
+    );
+    $schema = $this->getMockBuilder('Drupal\Core\Database\Schema')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $schema->expects($this->at(0))
+      ->method('tableExists')
+      ->with('migrate_map_sql_idmap_test')
+      ->will($this->returnValue(FALSE));
+    $schema->expects($this->at(1))
+      ->method('createTable')
+      ->with('migrate_map_sql_idmap_test', $map_table_schema);
+    // Now do the message table.
+    $fields = array();
+    $fields['msgid'] = array(
+      'type' => 'serial',
+      'unsigned' => TRUE,
+      'not null' => TRUE,
+    );
+    $fields['sourceid1'] = array(
+      'type' => 'int',
+      'not null' => TRUE,
+    );
+    $fields['level'] = array(
+      'type' => 'int',
+      'unsigned' => TRUE,
+      'not null' => TRUE,
+      'default' => 1,
+    );
+    $fields['message'] = array(
+      'type' => 'text',
+      'size' => 'medium',
+      'not null' => TRUE,
+    );
+    $table_schema = array(
+      'description' => 'Messages generated during a migration process',
+      'fields' => $fields,
+      'primary key' => array('msgid'),
+    );
+    $table_schema['indexes']['sourcekey'] = array('sourceid1');
+
+    $schema->expects($this->at(2))
+      ->method('tableExists')
+      ->with('migrate_message_sql_idmap_test')
+      ->will($this->returnValue(FALSE));
+    $schema->expects($this->at(3))
+      ->method('createTable')
+      ->with('migrate_message_sql_idmap_test', $table_schema);
+    $schema->expects($this->any())
+      ->method($this->anything());
+    $this->runEnsureTablesTest($schema);
+  }
+
+  /**
+   * Tests the ensureTables method when the tables exist.
+   */
+  public function testEnsureTablesExist() {
+    $schema = $this->getMockBuilder('Drupal\Core\Database\Schema')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $schema->expects($this->at(0))
+      ->method('tableExists')
+      ->with('migrate_map_sql_idmap_test')
+      ->will($this->returnValue(TRUE));
+    $schema->expects($this->at(1))
+      ->method('fieldExists')
+      ->with('migrate_map_sql_idmap_test', 'rollback_action')
+      ->will($this->returnValue(FALSE));
+    $field_schema = array(
+      'type' => 'int',
+      'size' => 'tiny',
+      'unsigned' => TRUE,
+      'not null' => TRUE,
+      'default' => 0,
+      'description' => 'Flag indicating what to do for this item on rollback',
+    );
+    $schema->expects($this->at(2))
+      ->method('addField')
+      ->with('migrate_map_sql_idmap_test', 'rollback_action', $field_schema);
+    $schema->expects($this->at(3))
+      ->method('fieldExists')
+      ->with('migrate_map_sql_idmap_test', 'hash')
+      ->will($this->returnValue(FALSE));
+    $field_schema = array(
+      'type' => 'varchar',
+      'length' => '64',
+      'not null' => FALSE,
+      'description' => 'Hash of source row data, for detecting changes',
+    );
+    $schema->expects($this->at(4))
+      ->method('addField')
+      ->with('migrate_map_sql_idmap_test', 'hash', $field_schema);
+    $schema->expects($this->exactly(5))
+      ->method($this->anything());
+    $this->runEnsureTablesTest($schema);
+  }
+
+  /**
+   * Actually run the test.
+   *
+   * @param array $schema
+   *   The mock schema object with expectations set. The Sql constructor calls
+   *   ensureTables() which in turn calls this object and the expectations on
+   *   it are the actual test and there are no additional asserts added.
+   */
+  protected function runEnsureTablesTest($schema) {
+    $database = $this->getMockBuilder('Drupal\Core\Database\Connection')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $database->expects($this->any())
+      ->method('schema')
+      ->will($this->returnValue($schema));
+    $migration = $this->getMigration();
+    $plugin = $this->getMock('Drupal\migrate\Plugin\MigrateSourceInterface');
+    $plugin->expects($this->any())
+      ->method('getIds')
+      ->will($this->returnValue(array(
+      'source_id_property' => array(
+        'type' => 'integer',
+      ),
+    )));
+    $migration->expects($this->any())
+      ->method('getSourcePlugin')
+      ->will($this->returnValue($plugin));
+    $plugin = $this->getMock('Drupal\migrate\Plugin\MigrateSourceInterface');
+    $plugin->expects($this->any())
+      ->method('getIds')
+      ->will($this->returnValue(array(
+      'destination_id_property' => array(
+        'type' => 'string',
+      ),
+    )));
+    $migration->expects($this->any())
+      ->method('getDestinationPlugin')
+      ->will($this->returnValue($plugin));
+    $map = new TestSqlIdMap($database, array(), 'sql', array(), $migration);
+    $map->getDatabase();
+  }
+
+}

core/modules/migrate/tests/src/Unit/MigrateSqlIdMapTest.php

@@ -0,0 +1,798 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\MigrateSqlIdMapTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\Core\Database\Driver\sqlite\Connection;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+use Drupal\migrate\Row;
+
+/**
+ * Tests the SQL ID map plugin.
+ *
+ * @group migrate
+ */
+class MigrateSqlIdMapTest extends MigrateTestCase {
+
+  /**
+   * The migration configuration, initialized to set the ID and destination IDs.
+   *
+   * @var array
+   */
+  protected $migrationConfiguration = [
+    'id' => 'sql_idmap_test',
+  ];
+
+  protected $sourceIds = [
+    'source_id_property' => [
+      'type' => 'string',
+    ],
+  ];
+
+  protected $destinationIds = [
+    'destination_id_property' => [
+      'type' => 'string',
+    ],
+  ];
+
+  /**
+   * The database connection.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $database;
+
+  public function setUp() {
+    $this->database = $this->getDatabase([]);
+  }
+
+  /**
+   * Saves a single ID mapping row in the database.
+   *
+   * @param array $map
+   *  The row to save.
+   */
+  protected function saveMap(array $map) {
+    $table = 'migrate_map_sql_idmap_test';
+
+    $schema = $this->database->schema();
+    // If the table already exists, add any columns which are in the map array,
+    // but don't yet exist in the table. Yay, flexibility!
+    if ($schema->tableExists($table)) {
+      foreach (array_keys($map) as $field) {
+        if (!$schema->fieldExists($table, $field)) {
+          $schema->addField($table, $field, ['type' => 'text']);
+        }
+      }
+    }
+    else {
+      $schema->createTable($table, $this->createSchemaFromRow($map));
+    }
+
+    $this->database->insert($table)->fields($map)->execute();
+  }
+
+  /**
+   * Creates a test SQL ID map plugin.
+   *
+   * @return \Drupal\Tests\migrate\Unit\TestSqlIdMap
+   *   A SQL ID map plugin test instance.
+   */
+  protected function getIdMap() {
+    $migration = $this->getMigration();
+
+    $plugin = $this->getMock('Drupal\migrate\Plugin\MigrateSourceInterface');
+    $plugin
+      ->method('getIds')
+      ->willReturn($this->sourceIds);
+    $migration
+      ->method('getSourcePlugin')
+      ->willReturn($plugin);
+
+    $plugin = $this->getMock('Drupal\migrate\Plugin\MigrateDestinationInterface');
+    $plugin
+      ->method('getIds')
+      ->willReturn($this->destinationIds);
+    $migration
+      ->method('getDestinationPlugin')
+      ->willReturn($plugin);
+
+    $id_map = new TestSqlIdMap($this->database, [], 'sql', [], $migration);
+    $migration
+      ->method('getIdMap')
+      ->willReturn($id_map);
+
+    return $id_map;
+  }
+
+  /**
+   * Sets defaults for SQL ID map plugin tests.
+   */
+  protected function idMapDefaults() {
+    $defaults = array(
+      'source_row_status' => MigrateIdMapInterface::STATUS_IMPORTED,
+      'rollback_action' => MigrateIdMapInterface::ROLLBACK_DELETE,
+      'hash' => '',
+    );
+    // By default, the PDO SQLite driver strongly prefers to return strings
+    // from SELECT queries. Even for columns that don't store strings. Even
+    // if the connection's STRINGIFY_FETCHES attribute is FALSE. This can cause
+    // assertSame() calls to fail, since 0 !== '0'. Casting these values to
+    // strings isn't the most elegant workaround, but it allows the assertions
+    // to pass properly.
+    if ($this->database->driver() == 'sqlite') {
+      $defaults['source_row_status'] = (string) $defaults['source_row_status'];
+      $defaults['rollback_action'] = (string) $defaults['rollback_action'];
+    }
+    return $defaults;
+  }
+
+  /**
+   * Tests the ID mapping method.
+   *
+   * Create two ID mappings and update the second to verify that:
+   * - saving new to empty tables work.
+   * - saving new to nonempty tables work.
+   * - updating work.
+   */
+  public function testSaveIdMapping() {
+    $source = array(
+      'source_id_property' => 'source_value',
+    );
+    $row = new Row($source, ['source_id_property' => []]);
+    $id_map = $this->getIdMap();
+    $id_map->saveIdMapping($row, ['destination_id_property' => 2]);
+    $expected_result = [
+      [
+        'sourceid1' => 'source_value',
+        'destid1' => 2,
+      ] + $this->idMapDefaults(),
+    ];
+    $this->queryResultTest($this->getIdMapContents(), $expected_result);
+    $source = [
+      'source_id_property' => 'source_value_1',
+    ];
+    $row = new Row($source, ['source_id_property' => []]);
+    $id_map->saveIdMapping($row, ['destination_id_property' => 3]);
+    $expected_result[] = [
+      'sourceid1' => 'source_value_1',
+      'destid1' => 3,
+    ] + $this->idMapDefaults();
+    $this->queryResultTest($this->getIdMapContents(), $expected_result);
+    $id_map->saveIdMapping($row, ['destination_id_property' => 4]);
+    $expected_result[1]['destid1'] = 4;
+    $this->queryResultTest($this->getIdMapContents(), $expected_result);
+  }
+
+  /**
+   * Tests the SQL ID map set message method.
+   */
+  public function testSetMessage() {
+    $message = $this->getMock('Drupal\migrate\MigrateMessageInterface');
+    $id_map = $this->getIdMap();
+    $id_map->setMessage($message);
+    $this->assertAttributeEquals($message, 'message', $id_map);
+  }
+
+  /**
+   * Tests the clear messages method.
+   */
+  public function testClearMessages() {
+    $message = 'Hello world.';
+    $expected_results = [0, 1, 2, 3];
+    $id_map = $this->getIdMap();
+
+    // Insert 4 message for later delete.
+    foreach ($expected_results as $key => $expected_result) {
+      $id_map->saveMessage([$key], $message);
+    }
+
+    // Truncate and check that 4 messages were deleted.
+    $this->assertEquals($id_map->messageCount(), 4);
+    $id_map->clearMessages();
+    $count = $id_map->messageCount();
+    $this->assertEquals($count, 0);
+  }
+
+  /**
+   * Tests the getRowsNeedingUpdate method for rows that need an update.
+   */
+  public function testGetRowsNeedingUpdate() {
+    $id_map = $this->getIdMap();
+    $row_statuses = [
+      MigrateIdMapInterface::STATUS_IMPORTED,
+      MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+      MigrateIdMapInterface::STATUS_IGNORED,
+      MigrateIdMapInterface::STATUS_FAILED,
+    ];
+    // Create a mapping row for each STATUS constant.
+    foreach ($row_statuses as $status) {
+      $source = ['source_id_property' => 'source_value_' . $status];
+      $row = new Row($source, ['source_id_property' => []]);
+      $destination = ['destination_id_property' => 'destination_value_' . $status];
+      $id_map->saveIdMapping($row, $destination, $status);
+      $expected_results[] = [
+        'sourceid1' => 'source_value_' . $status,
+        'destid1' => 'destination_value_' . $status,
+        'source_row_status' => $status,
+        'rollback_action' => MigrateIdMapInterface::ROLLBACK_DELETE,
+        'hash' => '',
+      ];
+      // Assert zero rows need an update.
+      if ($status == MigrateIdMapInterface::STATUS_IMPORTED) {
+        $rows_needing_update = $id_map->getRowsNeedingUpdate(1);
+        $this->assertCount(0, $rows_needing_update);
+      }
+    }
+    // Assert that test values exist.
+    $this->queryResultTest($this->getIdMapContents(), $expected_results);
+
+    // Assert a single row needs an update.
+    $row_needing_update = $id_map->getRowsNeedingUpdate(1);
+    $this->assertCount(1, $row_needing_update);
+
+    // Assert the row matches its original source.
+    $source_id = $expected_results[MigrateIdMapInterface::STATUS_NEEDS_UPDATE]['sourceid1'];
+    $test_row = $id_map->getRowBySource([$source_id]);
+    // $row_needing_update is an array of objects returned from the database,
+    // but $test_row is an array, so the cast is necessary.
+    $this->assertSame($test_row, (array) $row_needing_update[0]);
+
+    // Add additional row that needs an update.
+    $source = ['source_id_property' => 'source_value_multiple'];
+    $row = new Row($source, ['source_id_property' => []]);
+    $destination = ['destination_id_property' => 'destination_value_multiple'];
+    $id_map->saveIdMapping($row, $destination, MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
+
+    // Assert multiple rows need an update.
+    $rows_needing_update = $id_map->getRowsNeedingUpdate(2);
+    $this->assertCount(2, $rows_needing_update);
+  }
+
+  /**
+   * Tests the SQL ID map message count method by counting and saving messages.
+   */
+  public function testMessageCount() {
+    $message = 'Hello world.';
+    $expected_results = [0, 1, 2, 3];
+    $id_map = $this->getIdMap();
+
+    // Test count message multiple times starting from 0.
+    foreach ($expected_results as $key => $expected_result) {
+      $count = $id_map->messageCount();
+      $this->assertEquals($expected_result, $count);
+      $id_map->saveMessage([$key], $message);
+    }
+  }
+
+  /**
+   * Tests the SQL ID map save message method.
+   */
+  public function testMessageSave() {
+    $message = 'Hello world.';
+    $expected_results = [
+      1 => ['message' => $message, 'level' => MigrationInterface::MESSAGE_ERROR],
+      2 => ['message' => $message, 'level' => MigrationInterface::MESSAGE_WARNING],
+      3 => ['message' => $message, 'level' => MigrationInterface::MESSAGE_NOTICE],
+      4 => ['message' => $message, 'level' => MigrationInterface::MESSAGE_INFORMATIONAL],
+    ];
+    $id_map = $this->getIdMap();
+
+    foreach ($expected_results as $key => $expected_result) {
+      $id_map->saveMessage([$key], $message, $expected_result['level']);
+      $message_row = $this->database->select($id_map->messageTableName(), 'message')
+                       ->fields('message')
+                       ->condition('level', $expected_result['level'])
+                       ->condition('message', $expected_result['message'])
+                       ->execute()
+                       ->fetchAssoc();
+      $this->assertEquals($expected_result['message'], $message_row['message'], 'Message from database was read.');
+    }
+
+    // Insert with default level.
+    $message_default = 'Hello world default.';
+    $id_map->saveMessage([5], $message_default);
+    $message_row = $this->database->select($id_map->messageTableName(), 'message')
+                     ->fields('message')
+                     ->condition('level', MigrationInterface::MESSAGE_ERROR)
+                     ->condition('message', $message_default)
+                     ->execute()
+                     ->fetchAssoc();
+    $this->assertEquals($message_default, $message_row['message'], 'Message from database was read.');
+  }
+
+  /**
+   * Tests the getRowBySource method.
+   */
+  public function testGetRowBySource() {
+    $this->getDatabase([]);
+    $row = [
+      'sourceid1' => 'source_id_value_1',
+      'sourceid2' => 'source_id_value_2',
+      'destid1' => 'destination_id_value_1',
+    ] + $this->idMapDefaults();
+    $this->saveMap($row);
+    $row = [
+      'sourceid1' => 'source_id_value_3',
+      'sourceid2' => 'source_id_value_4',
+      'destid1' => 'destination_id_value_2',
+    ] + $this->idMapDefaults();
+    $this->saveMap($row);
+    $source_id_values = [$row['sourceid1'], $row['sourceid2']];
+    $id_map = $this->getIdMap();
+    $result_row = $id_map->getRowBySource($source_id_values);
+    $this->assertSame($row, $result_row);
+    $source_id_values = ['missing_value_1', 'missing_value_2'];
+    $result_row = $id_map->getRowBySource($source_id_values);
+    $this->assertFalse($result_row);
+  }
+
+  /**
+   * Data provider for testLookupDestinationIdMapping().
+   *
+   * Scenarios to test (for both hits and misses) are:
+   * - Single-value source ID to single-value destination ID.
+   * - Multi-value source ID to multi-value destination ID.
+   * - Single-value source ID to multi-value destination ID.
+   * - Multi-value source ID to single-value destination ID.
+   */
+  public function lookupDestinationIdMappingDataProvider() {
+    return [
+      [1, 1],
+      [2, 2],
+      [1, 2],
+      [2, 1],
+    ];
+  }
+
+  /**
+   * Performs destination ID test on source and destination fields.
+   *
+   * @param int $num_source_fields
+   *   Number of source fields to test.
+   * @param int $num_destination_fields
+   *   Number of destination fields to test.
+   * @dataProvider lookupDestinationIdMappingDataProvider
+   */
+  public function testLookupDestinationIdMapping($num_source_fields, $num_destination_fields) {
+    // Adjust the migration configuration according to the number of source and
+    // destination fields.
+    $this->sourceIds = [];
+    $this->destinationIds = [];
+    $source_id_values = [];
+    $nonexistent_id_values = [];
+    $row = $this->idMapDefaults();
+    for ($i = 1; $i <= $num_source_fields; $i++) {
+      $row["sourceid$i"] = "source_id_value_$i";
+      $source_id_values[] = "source_id_value_$i";
+      $nonexistent_id_values[] = "nonexistent_source_id_value_$i";
+      $this->sourceIds["source_id_property_$i"] = [];
+    }
+    $expected_result = [];
+    for ($i = 1; $i <= $num_destination_fields; $i++) {
+      $row["destid$i"] = "destination_id_value_$i";
+      $expected_result[] = "destination_id_value_$i";
+      $this->destinationIds["destination_id_property_$i"] = [];
+    }
+    $this->saveMap($row);
+    $id_map = $this->getIdMap();
+    // Test for a valid hit.
+    $destination_id = $id_map->lookupDestinationId($source_id_values);
+    $this->assertSame($expected_result, $destination_id);
+    // Test for a miss.
+    $destination_id = $id_map->lookupDestinationId($nonexistent_id_values);
+    $this->assertSame(0, count($destination_id));
+  }
+
+  /**
+   * Tests the getRowByDestination method.
+   */
+  public function testGetRowByDestination() {
+    $row = [
+      'sourceid1' => 'source_id_value_1',
+      'sourceid2' => 'source_id_value_2',
+      'destid1' => 'destination_id_value_1',
+    ] + $this->idMapDefaults();
+    $this->saveMap($row);
+    $row = [
+      'sourceid1' => 'source_id_value_3',
+      'sourceid2' => 'source_id_value_4',
+      'destid1' => 'destination_id_value_2',
+    ] + $this->idMapDefaults();
+    $this->saveMap($row);
+    $dest_id_values = [$row['destid1']];
+    $id_map = $this->getIdMap();
+    $result_row = $id_map->getRowByDestination($dest_id_values);
+    $this->assertSame($row, $result_row);
+    // This value does not exist.
+    $dest_id_values = ['invalid_destination_id_property'];
+    $id_map = $this->getIdMap();
+    $result_row = $id_map->getRowByDestination($dest_id_values);
+    $this->assertFalse($result_row);
+  }
+
+  /**
+   * Data provider for testLookupSourceIDMapping().
+   *
+   * Scenarios to test (for both hits and misses) are:
+   * - Single-value destination ID to single-value source ID.
+   * - Multi-value destination ID to multi-value source ID.
+   * - Single-value destination ID to multi-value source ID.
+   * - Multi-value destination ID to single-value source ID.
+   */
+  public function lookupSourceIDMappingDataProvider() {
+    return [
+      [1, 1],
+      [2, 2],
+      [1, 2],
+      [2, 1],
+    ];
+  }
+
+  /**
+   * Performs the source ID test on source and destination fields.
+   *
+   * @param int $num_source_fields
+   *   Number of source fields to test.
+   * @param int $num_destination_fields
+   *   Number of destination fields to test.
+   * @dataProvider lookupSourceIDMappingDataProvider
+   */
+  public function testLookupSourceIDMapping($num_source_fields, $num_destination_fields) {
+    // Adjust the migration configuration according to the number of source and
+    // destination fields.
+    $this->sourceIds = [];
+    $this->destinationIds = [];
+    $row = $this->idMapDefaults();
+    $expected_result = [];
+    for ($i = 1; $i <= $num_source_fields; $i++) {
+      $row["sourceid$i"] = "source_id_value_$i";
+      $expected_result[] = "source_id_value_$i";
+      $this->sourceIds["source_id_property_$i"] = [];
+    }
+    $destination_id_values = [];
+    $nonexistent_id_values = [];
+    for ($i = 1; $i <= $num_destination_fields; $i++) {
+      $row["destid$i"] = "destination_id_value_$i";
+      $destination_id_values[] = "destination_id_value_$i";
+      $nonexistent_id_values[] = "nonexistent_destination_id_value_$i";
+      $this->destinationIds["destination_id_property_$i"] = [];
+    }
+    $this->saveMap($row);
+    $id_map = $this->getIdMap();
+    // Test for a valid hit.
+    $source_id = $id_map->lookupSourceID($destination_id_values);
+    $this->assertSame($expected_result, $source_id);
+    // Test for a miss.
+    $source_id = $id_map->lookupSourceID($nonexistent_id_values);
+    $this->assertSame(0, count($source_id));
+  }
+
+  /**
+   * Tests the imported count method.
+   *
+   * Scenarios to test for:
+   * - No imports.
+   * - One import.
+   * - Multiple imports.
+   */
+  public function testImportedCount() {
+    $id_map = $this->getIdMap();
+    // Add a single failed row and assert zero imported rows.
+    $source = ['source_id_property' => 'source_value_failed'];
+    $row = new Row($source, ['source_id_property' => []]);
+    $destination = ['destination_id_property' => 'destination_value_failed'];
+    $id_map->saveIdMapping($row, $destination, MigrateIdMapInterface::STATUS_FAILED);
+    $this->assertSame(0, (int) $id_map->importedCount());
+
+    // Add an imported row and assert single count.
+    $source = ['source_id_property' => 'source_value_imported'];
+    $row = new Row($source, ['source_id_property' => []]);
+    $destination = ['destination_id_property' => 'destination_value_imported'];
+    $id_map->saveIdMapping($row, $destination, MigrateIdMapInterface::STATUS_IMPORTED);
+    $this->assertSame(1, (int) $id_map->importedCount());
+
+    // Add a row needing update and assert multiple imported rows.
+    $source = ['source_id_property' => 'source_value_update'];
+    $row = new Row($source, ['source_id_property' => []]);
+    $destination = ['destination_id_property' => 'destination_value_update'];
+    $id_map->saveIdMapping($row, $destination, MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
+    $this->assertSame(2, (int) $id_map->importedCount());
+  }
+
+  /**
+   * Tests the number of processed source rows.
+   *
+   * Scenarios to test for:
+   * - No processed rows.
+   * - One processed row.
+   * - Multiple processed rows.
+   */
+  public function testProcessedCount() {
+    $id_map = $this->getIdMap();
+    // Assert zero rows have been processed before adding rows.
+    $this->assertSame(0, (int) $id_map->processedCount());
+    $row_statuses = [
+      MigrateIdMapInterface::STATUS_IMPORTED,
+      MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+      MigrateIdMapInterface::STATUS_IGNORED,
+      MigrateIdMapInterface::STATUS_FAILED,
+    ];
+    // Create a mapping row for each STATUS constant.
+    foreach ($row_statuses as $status) {
+      $source = ['source_id_property' => 'source_value_' . $status];
+      $row = new Row($source, ['source_id_property' => []]);
+      $destination = ['destination_id_property' => 'destination_value_' . $status];
+      $id_map->saveIdMapping($row, $destination, $status);
+      if ($status == MigrateIdMapInterface::STATUS_IMPORTED) {
+        // Assert a single row has been processed.
+        $this->assertSame(1, (int) $id_map->processedCount());
+      }
+    }
+    // Assert multiple rows have been processed.
+    $this->assertSame(count($row_statuses), (int) $id_map->processedCount());
+  }
+
+  /**
+   * Data provider for testUpdateCount().
+   *
+   * Scenarios to test for:
+   * - No updates.
+   * - One update.
+   * - Multiple updates.
+   */
+  public function updateCountDataProvider() {
+    return [
+      [0],
+      [1],
+      [3],
+    ];
+  }
+
+  /**
+   * Performs the update count test with a given number of update rows.
+   *
+   * @param int $num_update_rows
+   *   The number of update rows to test.
+   * @dataProvider updateCountDataProvider
+   */
+  public function testUpdateCount($num_update_rows) {
+    for ($i = 0; $i < 5; $i++) {
+      $row = $this->idMapDefaults();
+      $row['sourceid1'] = "source_id_value_$i";
+      $row['destid1'] = "destination_id_value_$i";
+      $row['source_row_status'] = MigrateIdMapInterface::STATUS_IMPORTED;
+      $this->saveMap($row);
+    }
+    for (; $i < 5 + $num_update_rows; $i++) {
+      $row = $this->idMapDefaults();
+      $row['sourceid1'] = "source_id_value_$i";
+      $row['destid1'] = "destination_id_value_$i";
+      $row['source_row_status'] = MigrateIdMapInterface::STATUS_NEEDS_UPDATE;
+      $this->saveMap($row);
+    }
+    $id_map = $this->getIdMap();
+    $this->assertSame($num_update_rows, (int) $id_map->updateCount());
+  }
+
+  /**
+   * Data provider for testErrorCount().
+   *
+   * Scenarios to test for:
+   * - No errors.
+   * - One error.
+   * - Multiple errors.
+   */
+  public function errorCountDataProvider() {
+    return [
+      [0],
+      [1],
+      [3],
+    ];
+  }
+
+  /**
+   * Performs error count test with a given number of error rows.
+   *
+   * @param int $num_error_rows
+   *   Number of error rows to test.
+   * @dataProvider errorCountDataProvider
+   */
+  public function testErrorCount($num_error_rows) {
+    for ($i = 0; $i < 5; $i++) {
+      $row = $this->idMapDefaults();
+      $row['sourceid1'] = "source_id_value_$i";
+      $row['destid1'] = "destination_id_value_$i";
+      $row['source_row_status'] = MigrateIdMapInterface::STATUS_IMPORTED;
+      $this->saveMap($row);
+    }
+    for (; $i < 5 + $num_error_rows; $i++) {
+      $row = $this->idMapDefaults();
+      $row['sourceid1'] = "source_id_value_$i";
+      $row['destid1'] = "destination_id_value_$i";
+      $row['source_row_status'] = MigrateIdMapInterface::STATUS_FAILED;
+      $this->saveMap($row);
+    }
+
+    $this->assertSame($num_error_rows, (int) $this->getIdMap()->errorCount());
+  }
+
+  /**
+   * Tests setting a row source_row_status to STATUS_NEEDS_UPDATE.
+   */
+  public function testSetUpdate() {
+    $id_map = $this->getIdMap();
+    $row_statuses = [
+      MigrateIdMapInterface::STATUS_IMPORTED,
+      MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+      MigrateIdMapInterface::STATUS_IGNORED,
+      MigrateIdMapInterface::STATUS_FAILED,
+    ];
+    // Create a mapping row for each STATUS constant.
+    foreach ($row_statuses as $status) {
+      $source = ['source_id_property' => 'source_value_' . $status];
+      $row = new Row($source, ['source_id_property' => []]);
+      $destination = ['destination_id_property' => 'destination_value_' . $status];
+      $id_map->saveIdMapping($row, $destination, $status);
+      $expected_results[] = [
+        'sourceid1' => 'source_value_' . $status,
+        'destid1' => 'destination_value_' . $status,
+        'source_row_status' => $status,
+        'rollback_action' => MigrateIdMapInterface::ROLLBACK_DELETE,
+        'hash' => '',
+      ];
+    }
+    // Assert that test values exist.
+    $this->queryResultTest($this->getIdMapContents(), $expected_results);
+    // Mark each row as STATUS_NEEDS_UPDATE.
+    foreach ($row_statuses as $status) {
+      $id_map->setUpdate(['source_value_' . $status]);
+    }
+    // Update expected results.
+    foreach ($expected_results as $key => $value) {
+      $expected_results[$key]['source_row_status'] = MigrateIdMapInterface::STATUS_NEEDS_UPDATE;
+    }
+    // Assert that updated expected values match.
+    $this->queryResultTest($this->getIdMapContents(), $expected_results);
+    // Assert an exception is thrown when source identifiers are not provided.
+    try {
+      $id_map->setUpdate([]);
+      $this->assertFalse(FALSE, 'MigrateException not thrown, when source identifiers were provided to update.');
+    }
+    catch (MigrateException $e) {
+      $this->assertTrue(TRUE, "MigrateException thrown, when source identifiers were not provided to update.");
+    }
+  }
+
+  /**
+   * Tests prepareUpdate().
+   */
+  public function testPrepareUpdate() {
+    $id_map = $this->getIdMap();
+    $row_statuses = [
+      MigrateIdMapInterface::STATUS_IMPORTED,
+      MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+      MigrateIdMapInterface::STATUS_IGNORED,
+      MigrateIdMapInterface::STATUS_FAILED,
+    ];
+
+    // Create a mapping row for each STATUS constant.
+    foreach ($row_statuses as $status) {
+      $source = ['source_id_property' => 'source_value_' . $status];
+      $row = new Row($source, ['source_id_property' => []]);
+      $destination = ['destination_id_property' => 'destination_value_' . $status];
+      $id_map->saveIdMapping($row, $destination, $status);
+      $expected_results[] = [
+        'sourceid1' => 'source_value_' . $status,
+        'destid1' => 'destination_value_' . $status,
+        'source_row_status' => $status,
+        'rollback_action' => MigrateIdMapInterface::ROLLBACK_DELETE,
+        'hash' => '',
+      ];
+    }
+
+    // Assert that test values exist.
+    $this->queryResultTest($this->getIdMapContents(), $expected_results);
+
+    // Mark all rows as STATUS_NEEDS_UPDATE.
+    $id_map->prepareUpdate();
+
+    // Update expected results.
+    foreach ($expected_results as $key => $value) {
+      $expected_results[$key]['source_row_status'] = MigrateIdMapInterface::STATUS_NEEDS_UPDATE;
+    }
+    // Assert that updated expected values match.
+    $this->queryResultTest($this->getIdMapContents(), $expected_results);
+  }
+
+  /**
+   * Tests the destroy method.
+   *
+   * Scenarios to test for:
+   * - No errors.
+   * - One error.
+   * - Multiple errors.
+   */
+  public function testDestroy() {
+    $id_map = $this->getIdMap();
+    // Initialize the id map.
+    $id_map->getDatabase();
+    $map_table_name = $id_map->mapTableName();
+    $message_table_name = $id_map->messageTableName();
+    $row = new Row(['source_id_property' => 'source_value'], ['source_id_property' => []]);
+    $id_map->saveIdMapping($row, ['destination_id_property' => 2]);
+    $id_map->saveMessage(['source_value'], 'A message');
+    $this->assertTrue($this->database->schema()->tableExists($map_table_name),
+                      "$map_table_name exists");
+    $this->assertTrue($this->database->schema()->tableExists($message_table_name),
+                      "$message_table_name exists");
+    $id_map->destroy();
+    $this->assertFalse($this->database->schema()->tableExists($map_table_name),
+                       "$map_table_name does not exist");
+    $this->assertFalse($this->database->schema()->tableExists($message_table_name),
+                       "$message_table_name does not exist");
+  }
+
+  /**
+   * Tests the getQualifiedMapTable method with a prefixed database.
+   */
+  public function testGetQualifiedMapTablePrefix() {
+    $connection_options = [
+      'database' => ':memory:',
+      'prefix' => 'prefix',
+    ];
+    $pdo = Connection::open($connection_options);
+    $this->database = new Connection($pdo, $connection_options);
+    $qualified_map_table = $this->getIdMap()->getQualifiedMapTableName();
+    // The SQLite driver is a special flower. It will prefix tables with
+    // PREFIX.TABLE, instead of the standard PREFIXTABLE.
+    // @see \Drupal\Core\Database\Driver\sqlite\Connection::__construct()
+    $this->assertEquals('prefix.migrate_map_sql_idmap_test', $qualified_map_table);
+  }
+
+  /**
+   * Tests all the iterator methods in one swing.
+   *
+   * The iterator methods are:
+   * - Sql::rewind()
+   * - Sql::next()
+   * - Sql::valid()
+   * - Sql::key()
+   * - Sql::current()
+   */
+  public function testIterators() {
+    for ($i = 0; $i < 3; $i++) {
+      $row = $this->idMapDefaults();
+      $row['sourceid1'] = "source_id_value_$i";
+      $row['destid1'] = "destination_id_value_$i";
+      $row['source_row_status'] = MigrateIdMapInterface::STATUS_IMPORTED;
+      $expected_results[serialize(['sourceid1' => $row['sourceid1']])] = ['destid1' => $row['destid1']];
+      $this->saveMap($row);
+    }
+
+    $this->assertSame(iterator_to_array($this->getIdMap()), $expected_results);
+  }
+
+  private function getIdMapContents() {
+    $result = $this->database
+      ->select('migrate_map_sql_idmap_test', 't')
+      ->fields('t')
+      ->execute();
+
+    // The return value needs to be countable, or it will fail certain
+    // assertions. iterator_to_array() will not suffice because it won't
+    // respect the PDO fetch mode, if specified.
+    $contents = [];
+    foreach ($result as $row) {
+      $contents[] = (array) $row;
+    }
+    return $contents;
+  }
+
+}

core/modules/migrate/tests/src/Unit/MigrateSqlSourceTestCase.php

@@ -0,0 +1,118 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\MigrateSqlSourceTestCase.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+/**
+ * Base class for Migrate module source unit tests.
+ */
+abstract class MigrateSqlSourceTestCase extends MigrateTestCase {
+
+  /**
+   * The tested source plugin.
+   *
+   * @var \Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase.
+   */
+  protected $source;
+
+  /**
+   * The database contents.
+   *
+   * Database contents represents a mocked database. It should contain an
+   * associative array with the table name as key, and as many nested arrays as
+   * the number of mocked rows. Each of those faked rows must be another array
+   * with the column name as the key and the value as the cell.
+   *
+   * @var array
+   */
+  protected $databaseContents = array();
+
+  /**
+   * The plugin class under test.
+   *
+   * The plugin system is not working during unit testing so the source plugin
+   * class needs to be manually specified.
+   *
+   * @var string
+   */
+  const PLUGIN_CLASS = '';
+
+  /**
+   * The high water mark at the beginning of the import operation.
+   *
+   * Once the migration is run, we save a mark of the migrated sources, so the
+   * migration can run again and update only new sources or changed sources.
+   *
+   * @var string
+   */
+  const ORIGINAL_HIGH_WATER = '';
+
+  /**
+   * Expected results after the source parsing.
+   *
+   * @var array
+   */
+  protected $expectedResults = array();
+
+  /**
+   * The source plugin instance under test.
+   *
+   * @var \Drupal\migrate\Plugin\MigrateSourceInterface
+   */
+  protected $plugin;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    $module_handler = $this->getMock('Drupal\Core\Extension\ModuleHandlerInterface');
+    $entity_manager = $this->getMock('Drupal\Core\Entity\EntityManagerInterface');
+
+    $migration = $this->getMigration();
+    $migration->expects($this->any())
+      ->method('getHighWater')
+      ->will($this->returnValue(static::ORIGINAL_HIGH_WATER));
+
+    // Setup the plugin.
+    $plugin_class = static::PLUGIN_CLASS;
+    $plugin = new $plugin_class($this->migrationConfiguration['source'], $this->migrationConfiguration['source']['plugin'], array(), $migration, $entity_manager);
+
+    // Do some reflection to set the database and moduleHandler.
+    $plugin_reflection = new \ReflectionClass($plugin);
+    $database_property = $plugin_reflection->getProperty('database');
+    $database_property->setAccessible(TRUE);
+    $module_handler_property = $plugin_reflection->getProperty('moduleHandler');
+    $module_handler_property->setAccessible(TRUE);
+
+    // Set the database and the module handler onto our plugin.
+    $database_property->setValue($plugin, $this->getDatabase($this->databaseContents + array('test_map' => array())));
+    $module_handler_property->setValue($plugin, $module_handler);
+
+    $plugin->setStringTranslation($this->getStringTranslationStub());
+    $migration->expects($this->any())
+      ->method('getSourcePlugin')
+      ->will($this->returnValue($plugin));
+    $this->source = $plugin;
+  }
+
+  /**
+   * Test the source returns the same rows as expected.
+   */
+  public function testRetrieval() {
+    $this->queryResultTest($this->source, $this->expectedResults);
+  }
+
+  /**
+   * @param \Drupal\migrate\Row $row
+   * @param string $key
+   * @return mixed
+   */
+  protected function getValue($row, $key) {
+    return $row->getSourceProperty($key);
+  }
+
+}

core/modules/migrate/tests/src/Unit/MigrateTestCase.php

@@ -0,0 +1,162 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\MigrateTestCase.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\Core\Database\Driver\sqlite\Connection;
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Provides setup and helper methods for Migrate module tests.
+ */
+abstract class MigrateTestCase extends UnitTestCase {
+
+  protected $migrationConfiguration = [];
+
+  /**
+   * Retrieve a mocked migration.
+   *
+   * @return \Drupal\migrate\Entity\MigrationInterface|\PHPUnit_Framework_MockObject_MockObject
+   *   The mocked migration.
+   */
+  protected function getMigration() {
+    $this->migrationConfiguration += ['migrationClass' => 'Drupal\migrate\Entity\Migration'];
+    $this->idMap = $this->getMock('Drupal\migrate\Plugin\MigrateIdMapInterface');
+
+    $this->idMap->expects($this->any())
+      ->method('getQualifiedMapTableName')
+      ->will($this->returnValue('test_map'));
+
+    $migration = $this->getMockBuilder($this->migrationConfiguration['migrationClass'])
+      ->disableOriginalConstructor()
+      ->getMock();
+    $migration->expects($this->any())
+      ->method('checkRequirements')
+      ->will($this->returnValue(TRUE));
+    $migration->expects($this->any())
+      ->method('getIdMap')
+      ->will($this->returnValue($this->idMap));
+    $configuration = &$this->migrationConfiguration;
+    $migration->expects($this->any())->method('get')->will($this->returnCallback(function ($argument) use (&$configuration) {
+      return isset($configuration[$argument]) ? $configuration[$argument] : '';
+    }));
+    $migration->expects($this->any())->method('set')->will($this->returnCallback(function ($argument, $value) use (&$configuration) {
+      $configuration[$argument] = $value;
+    }));
+    $migration->expects($this->any())
+      ->method('id')
+      ->will($this->returnValue($configuration['id']));
+    return $migration;
+  }
+
+  /**
+   * Get an SQLite database connection object for use in tests.
+   *
+   * @param array $database_contents
+   *   The database contents faked as an array. Each key is a table name, each
+   *   value is a list of table rows, an associative array of field => value.
+   * @param array $connection_options
+   *  (optional) Options for the database connection.
+   *
+   * @return \Drupal\Core\Database\Driver\sqlite\Connection
+   *   The database connection.
+   */
+  protected function getDatabase(array $database_contents, $connection_options = []) {
+    if (extension_loaded('pdo_sqlite')) {
+      $connection_options['database'] = ':memory:';
+      $pdo = Connection::open($connection_options);
+      $connection = new Connection($pdo, $connection_options);
+    }
+    else {
+      $this->markTestSkipped('The pdo_sqlite extension is not available.');
+    }
+
+    // Initialize the DIC with a fake module handler for alterable queries.
+    $container = new ContainerBuilder();
+    $container->set('module_handler', $this->getMock('\Drupal\Core\Extension\ModuleHandlerInterface'));
+    \Drupal::setContainer($container);
+
+    // Create the tables and load them up with data, skipping empty ones.
+    foreach (array_filter($database_contents) as $table => $rows) {
+      $pilot_row = reset($rows);
+      $connection->schema()->createTable($table, $this->createSchemaFromRow($pilot_row));
+
+      $insert = $connection->insert($table)->fields(array_keys($pilot_row));
+      array_walk($rows, [$insert, 'values']);
+      $insert->execute();
+    }
+
+    return $connection;
+  }
+
+  /**
+   * Generates a table schema from a row.
+   *
+   * @param array $row
+   *  The reference row on which to base the schema.
+   *
+   * @return array
+   *  The Schema API-ready table schema.
+   */
+  protected function createSchemaFromRow(array $row) {
+    // SQLite uses loose ("affinity") typing, so it's OK for every column
+    // to be a text field.
+    $fields = array_map(function() { return ['type' => 'text']; }, $row);
+    return ['fields' => $fields];
+  }
+
+  /**
+   * Tests a query
+   *
+   * @param array|\Traversable
+   *   The countable. foreach-able actual results if a query is being run.
+   */
+  public function queryResultTest($iter, $expected_results) {
+    $this->assertSame(count($expected_results), count($iter), 'Number of results match');
+    $count = 0;
+    foreach ($iter as $data_row) {
+      $expected_row = $expected_results[$count];
+      $count++;
+      foreach ($expected_row as $key => $expected_value) {
+        $this->retrievalAssertHelper($expected_value, $this->getValue($data_row, $key), sprintf('Value matches for key "%s"', $key));
+      }
+    }
+    $this->assertSame(count($expected_results), $count);
+  }
+
+  /**
+   * @param array $row
+   * @param string $key
+   * @return mixed
+   */
+  protected function getValue($row, $key) {
+    return $row[$key];
+  }
+
+  /**
+   * Asserts tested values during test retrieval.
+   *
+   * @param mixed $expected_value
+   *   The incoming expected value to test.
+   * @param mixed $actual_value
+   *   The incoming value itself.
+   * @param string $message
+   *   The tested result as a formatted string.
+   */
+  protected function retrievalAssertHelper($expected_value, $actual_value, $message) {
+    if (is_array($expected_value)) {
+      foreach ($expected_value as $k => $v) {
+        $this->retrievalAssertHelper($v, $actual_value[$k], $message . '[' . $k . ']');
+      }
+    }
+    else {
+      $this->assertSame((string) $expected_value, (string) $actual_value, $message);
+    }
+  }
+
+}

core/modules/migrate/tests/src/Unit/MigrationTest.php

@@ -0,0 +1,148 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\MigrationTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\migrate\Entity\Migration;
+use Drupal\migrate\Exception\RequirementsException;
+use Drupal\migrate\Plugin\MigrateDestinationInterface;
+use Drupal\migrate\Plugin\MigrateSourceInterface;
+use Drupal\migrate\Plugin\RequirementsInterface;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\migrate\Entity\Migration
+ * @group Migration
+ */
+class MigrationTest extends UnitTestCase {
+
+  /**
+   * Tests checking requirements for source plugins.
+   *
+   * @covers ::checkRequirements
+   *
+   * @expectedException \Drupal\migrate\Exception\RequirementsException
+   * @expectedExceptionMessage Missing source requirement
+   */
+  public function testRequirementsForSourcePlugin() {
+    $migration = new TestMigration();
+
+    $source_plugin = $this->getMock('Drupal\Tests\migrate\Unit\RequirementsAwareSourceInterface');
+    $source_plugin->expects($this->once())
+      ->method('checkRequirements')
+      ->willThrowException(new RequirementsException('Missing source requirement', ['key' => 'value']));
+    $destination_plugin = $this->getMock('Drupal\Tests\migrate\Unit\RequirementsAwareDestinationInterface');
+
+    $migration->setSourcePlugin($source_plugin);
+    $migration->setDestinationPlugin($destination_plugin);
+
+    $migration->checkRequirements();
+  }
+
+  /**
+   * Tests checking requirements for destination plugins.
+   *
+   * @covers ::checkRequirements
+   *
+   * @expectedException \Drupal\migrate\Exception\RequirementsException
+   * @expectedExceptionMessage Missing destination requirement
+   */
+  public function testRequirementsForDestinationPlugin() {
+    $migration = new TestMigration();
+
+    $source_plugin = $this->getMock('Drupal\migrate\Plugin\MigrateSourceInterface');
+    $destination_plugin = $this->getMock('Drupal\Tests\migrate\Unit\RequirementsAwareDestinationInterface');
+    $destination_plugin->expects($this->once())
+      ->method('checkRequirements')
+      ->willThrowException(new RequirementsException('Missing destination requirement', ['key' => 'value']));
+
+    $migration->setSourcePlugin($source_plugin);
+    $migration->setDestinationPlugin($destination_plugin);
+
+    $migration->checkRequirements();
+  }
+
+  /**
+   * Tests checking requirements for destination plugins.
+   *
+   * @covers ::checkRequirements
+   *
+   * @expectedException \Drupal\migrate\Exception\RequirementsException
+   * @expectedExceptionMessage Missing migrations test_a, test_c
+   */
+  public function testRequirementsForMigrations() {
+    $migration = new TestMigration();
+
+    // Setup source and destination plugins without any requirements.
+    $source_plugin = $this->getMock('Drupal\migrate\Plugin\MigrateSourceInterface');
+    $destination_plugin = $this->getMock('Drupal\migrate\Plugin\MigrateDestinationInterface');
+    $migration->setSourcePlugin($source_plugin);
+    $migration->setDestinationPlugin($destination_plugin);
+
+    $entity_manager = $this->getMock('Drupal\Core\Entity\EntityManagerInterface');
+    $migration->setEntityManager($entity_manager);
+
+    // We setup the requirements that test_a doesn't exist and test_c is not
+    // completed yet.
+    $migration->setRequirements(['test_a', 'test_b', 'test_c', 'test_d']);
+
+    $migration_b = $this->getMock('Drupal\migrate\Entity\MigrationInterface');
+    $migration_c = $this->getMock('Drupal\migrate\Entity\MigrationInterface');
+    $migration_d = $this->getMock('Drupal\migrate\Entity\MigrationInterface');
+
+    $migration_b->expects($this->once())
+      ->method('isComplete')
+      ->willReturn(TRUE);
+    $migration_c->expects($this->once())
+      ->method('isComplete')
+      ->willReturn(FALSE);
+    $migration_d->expects($this->once())
+      ->method('isComplete')
+      ->willReturn(TRUE);
+
+    $migration_storage = $this->getMock('Drupal\Core\Entity\EntityStorageInterface');
+    $migration_storage->expects($this->once())
+      ->method('loadMultiple')
+      ->with(['test_a', 'test_b', 'test_c', 'test_d'])
+      ->willReturn(['test_b' => $migration_b, 'test_c' => $migration_c, 'test_d' => $migration_d]);
+    $entity_manager->expects($this->once())
+      ->method('getStorage')
+      ->with('migration')
+      ->willReturn($migration_storage);
+
+    $migration->checkRequirements();
+  }
+
+}
+
+class TestMigration extends Migration {
+
+  public function __construct() {
+  }
+
+  public function setRequirements(array $requirements) {
+    $this->requirements = $requirements;
+  }
+
+  public function setSourcePlugin(MigrateSourceInterface $source_plugin) {
+    $this->sourcePlugin = $source_plugin;
+  }
+
+  public function setDestinationPlugin(MigrateDestinationInterface $destination_plugin) {
+    $this->destinationPlugin = $destination_plugin;
+  }
+
+  public function setEntityManager(EntityManagerInterface $entity_manager) {
+    $this->entityManager = $entity_manager;
+  }
+
+}
+
+interface RequirementsAwareSourceInterface extends MigrateSourceInterface, RequirementsInterface {}
+
+interface RequirementsAwareDestinationInterface extends MigrateDestinationInterface, RequirementsInterface {}

core/modules/migrate/tests/src/Unit/RowTest.php

@@ -0,0 +1,250 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\RowTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
+use Drupal\migrate\Row;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\migrate\Row
+ * @group migrate
+ */
+class RowTest extends UnitTestCase {
+
+  /**
+   * The source IDs.
+   *
+   * @var array
+   */
+  protected $testSourceIds = array(
+    'nid' => 'Node ID',
+  );
+
+  /**
+   * The test values.
+   *
+   * @var array
+   */
+  protected $testValues = array(
+    'nid' => 1,
+    'title' => 'node 1',
+  );
+
+  /**
+   * The test hash.
+   *
+   * @var string
+   */
+  protected $testHash = '85795d4cde4a2425868b812cc88052ecd14fc912e7b9b4de45780f66750e8b1e';
+
+  /**
+   * The test hash after changing title value to 'new title'.
+   *
+   * @var string
+   */
+  protected $testHashMod = '9476aab0b62b3f47342cc6530441432e5612dcba7ca84115bbab5cceaca1ecb3';
+
+  /**
+   * Tests object creation: empty.
+   */
+  public function testRowWithoutData() {
+    $row = new Row(array(), array());
+    $this->assertSame(array(), $row->getSource(), 'Empty row');
+  }
+
+  /**
+   * Tests object creation: basic.
+   */
+  public function testRowWithBasicData() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    $this->assertSame($this->testValues, $row->getSource(), 'Row with data, simple id.');
+  }
+
+  /**
+   * Tests object creation: multiple source IDs.
+   */
+  public function testRowWithMultipleSourceIds() {
+    $multi_source_ids = $this->testSourceIds + array('vid' => 'Node revision');
+    $multi_source_ids_values = $this->testValues + array('vid' => 1);
+    $row = new Row($multi_source_ids_values, $multi_source_ids);
+    $this->assertSame($multi_source_ids_values, $row->getSource(), 'Row with data, multifield id.');
+  }
+
+  /**
+   * Tests object creation: invalid values.
+   *
+   * @expectedException \Exception
+   */
+  public function testRowWithInvalidData() {
+    $invalid_values = array(
+      'title' => 'node X',
+    );
+    $row = new Row($invalid_values, $this->testSourceIds);
+  }
+
+  /**
+   * Tests source immutability after freeze.
+   *
+   * @expectedException \Exception
+   */
+  public function testSourceFreeze() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    $row->rehash();
+    $this->assertSame($this->testHash, $row->getHash(), 'Correct hash.');
+    $row->setSourceProperty('title', 'new title');
+    $row->rehash();
+    $this->assertSame($this->testHashMod, $row->getHash(), 'Hash changed correctly.');
+    $row->freezeSource();
+    $row->setSourceProperty('title', 'new title');
+  }
+
+  /**
+   * Tests setting on a frozen row.
+   *
+   * @expectedException \Exception
+   * @expectedExceptionMessage The source is frozen and can't be changed any more
+   */
+  public function testSetFrozenRow() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    $row->freezeSource();
+    $row->setSourceProperty('title', 'new title');
+  }
+
+  /**
+   * Tests hashing.
+   */
+  public function testHashing() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    $this->assertSame('', $row->getHash(), 'No hash at creation');
+    $row->rehash();
+    $this->assertSame($this->testHash, $row->getHash(), 'Correct hash.');
+    $row->rehash();
+    $this->assertSame($this->testHash, $row->getHash(), 'Correct hash even doing it twice.');
+
+    // Set the map to needs update.
+    $test_id_map = array(
+      'original_hash' => '',
+      'hash' => '',
+      'source_row_status' => MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+    );
+    $row->setIdMap($test_id_map);
+    $this->assertTrue($row->needsUpdate());
+
+    $row->rehash();
+    $this->assertSame($this->testHash, $row->getHash(), 'Correct hash even if id_mpa have changed.');
+    $row->setSourceProperty('title', 'new title');
+    $row->rehash();
+    $this->assertSame($this->testHashMod, $row->getHash(), 'Hash changed correctly.');
+    // Check hash calculation algorithm.
+    $hash = hash('sha256', serialize($row->getSource()));
+    $this->assertSame($hash, $row->getHash());
+    // Check length of generated hash used for mapping schema.
+    $this->assertSame(64, strlen($row->getHash()));
+
+    // Set the map to successfully imported.
+    $test_id_map = array(
+      'original_hash' => '',
+      'hash' => '',
+      'source_row_status' => MigrateIdMapInterface::STATUS_IMPORTED,
+    );
+    $row->setIdMap($test_id_map);
+    $this->assertFalse($row->needsUpdate());
+
+    // Set the same hash value and ensure it was not changed.
+    $random = $this->randomMachineName();
+    $test_id_map = array(
+      'original_hash' => $random,
+      'hash' => $random,
+      'source_row_status' => MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+    );
+    $row->setIdMap($test_id_map);
+    $this->assertFalse($row->changed());
+
+    // Set different has values to ensure it is marked as changed.
+    $test_id_map = array(
+      'original_hash' => $this->randomMachineName(),
+      'hash' => $this->randomMachineName(),
+      'source_row_status' => MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+    );
+    $row->setIdMap($test_id_map);
+    $this->assertTrue($row->changed());
+  }
+
+  /**
+   * Tests getting/setting the ID Map.
+   *
+   * @covers ::setIdMap
+   * @covers ::getIdMap
+   */
+  public function testGetSetIdMap() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    $test_id_map = array(
+      'original_hash' => '',
+      'hash' => '',
+      'source_row_status' => MigrateIdMapInterface::STATUS_NEEDS_UPDATE,
+    );
+    $row->setIdMap($test_id_map);
+    $this->assertEquals($test_id_map, $row->getIdMap());
+  }
+
+  /**
+   * Tests the source ID.
+   */
+  public function testSourceIdValues() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    $this->assertSame(array('nid' => $this->testValues['nid']), $row->getSourceIdValues());
+  }
+
+  /**
+   * Tests getting the source property.
+   *
+   * @covers ::getSourceProperty
+   */
+  public function testGetSourceProperty() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    $this->assertSame($this->testValues['nid'], $row->getSourceProperty('nid'));
+    $this->assertSame($this->testValues['title'], $row->getSourceProperty('title'));
+    $this->assertNull($row->getSourceProperty('non_existing'));
+  }
+
+  /**
+   * Tests setting and getting the destination.
+   */
+  public function testDestination() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    $this->assertEmpty($row->getDestination());
+    $this->assertFalse($row->hasDestinationProperty('nid'));
+
+    // Set a destination.
+    $row->setDestinationProperty('nid', 2);
+    $this->assertTrue($row->hasDestinationProperty('nid'));
+    $this->assertEquals(array('nid' => 2), $row->getDestination());
+  }
+
+  /**
+   * Tests setting/getting multiple destination IDs.
+   */
+  public function testMultipleDestination() {
+    $row = new Row($this->testValues, $this->testSourceIds);
+    // Set some deep nested values.
+    $row->setDestinationProperty('image/alt', 'alt text');
+    $row->setDestinationProperty('image/fid', 3);
+
+    $this->assertTrue($row->hasDestinationProperty('image'));
+    $this->assertFalse($row->hasDestinationProperty('alt'));
+    $this->assertFalse($row->hasDestinationProperty('fid'));
+
+    $destination = $row->getDestination();
+    $this->assertEquals('alt text', $destination['image']['alt']);
+    $this->assertEquals(3, $destination['image']['fid']);
+    $this->assertEquals('alt text', $row->getDestinationProperty('image/alt'));
+    $this->assertEquals(3, $row->getDestinationProperty('image/fid'));
+  }
+
+}

core/modules/migrate/tests/src/Unit/SqlBaseTest.php

@@ -0,0 +1,177 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\SqlBaseTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\migrate\Plugin\migrate\source\SqlBase;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Tests the SqlBase class.
+ *
+ * @group migrate
+ */
+class SqlBaseTest extends UnitTestCase {
+
+  /**
+   * @param bool $expected_result
+   *   The expected result.
+   * @param bool $id_map_is_sql
+   *   TRUE if we want getIdMap() to return an instance of Sql.
+   * @param bool $with_id_map
+   *   TRUE if we want the id map to have a valid map of ids.
+   * @param array $source_options
+   *   An array of connection options for the source connection.
+   * @param array $idmap_options
+   *   An array of connection options for the id map connection.
+   *
+   * @dataProvider sqlBaseTestProvider
+   */
+  public function testMapJoinable($expected_result, $id_map_is_sql, $with_id_map, $source_options = [], $idmap_options = []) {
+    // Setup a connection object.
+    $source_connection = $this->getMockBuilder('Drupal\Core\Database\Connection')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $source_connection->expects($id_map_is_sql && $with_id_map ? $this->once() : $this->never())
+      ->method('getConnectionOptions')
+      ->willReturn($source_options);
+
+    // Setup the id map connection.
+    $idmap_connection = $this->getMockBuilder('Drupal\Core\Database\Connection')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $idmap_connection->expects($id_map_is_sql && $with_id_map ? $this->once() : $this->never())
+      ->method('getConnectionOptions')
+      ->willReturn($idmap_options);
+
+    // Setup the Sql object.
+    $sql = $this->getMockBuilder('Drupal\migrate\Plugin\migrate\id_map\Sql')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $sql->expects($id_map_is_sql && $with_id_map ? $this->once() : $this->never())
+      ->method('getDatabase')
+      ->willReturn($idmap_connection);
+
+    // Setup a migration entity.
+    $migration = $this->getMock('Drupal\migrate\Entity\MigrationInterface');
+    $migration->expects($with_id_map ? $this->once() : $this->never())
+      ->method('getIdMap')
+      ->willReturn($id_map_is_sql ? $sql : NULL);
+
+    // Create our SqlBase test class.
+    $sql_base = new TestSqlBase();
+    $sql_base->setMigration($migration);
+    $sql_base->setDatabase($source_connection);
+
+    // Configure the idMap to make the check in mapJoinable() pass.
+    if ($with_id_map) {
+      $sql_base->setIds([
+        'uid' => ['type' => 'integer', 'alias' => 'u'],
+      ]);
+    }
+
+    $this->assertEquals($expected_result, $sql_base->mapJoinable());
+  }
+
+  /**
+   * The data provider for SqlBase.
+   *
+   * @return array
+   *   An array of data per test run.
+   */
+  public function sqlBaseTestProvider() {
+    return [
+      // Source ids are empty so mapJoinable() is false.
+      [FALSE, FALSE, FALSE],
+      // Still false because getIdMap() is not a subclass of Sql.
+      [FALSE, FALSE, TRUE],
+      // Test mapJoinable() returns false when source and id connection options
+      // differ.
+      [FALSE, TRUE, TRUE, ['username' => 'different_from_map', 'password' => 'different_from_map'], ['username' => 'different_from_source', 'password' => 'different_from_source']],
+      // Returns true because source and id map connection options are the same.
+      [TRUE, TRUE, TRUE, ['username' => 'same_value', 'password' => 'same_value'], ['username' => 'same_value', 'password' => 'same_value']],
+    ];
+  }
+
+}
+
+class TestSqlBase extends SqlBase {
+
+  protected $database;
+  protected $ids;
+
+  /**
+   * Override the constructor so we can create one easily.
+   */
+  public function __construct() {}
+
+  /**
+   * Allows us to set the database during tests.
+   *
+   * @param mixed $database
+   *   The database mock object.
+   */
+  public function setDatabase($database) {
+    $this->database = $database;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDatabase() {
+    return $this->database;
+  }
+
+  /**
+   * Allows us to set the migration during the test.
+   *
+   * @param mixed $migration
+   *   The migration mock.
+   */
+  public function setMigration($migration) {
+    $this->migration = $migration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function mapJoinable() {
+    return parent::mapJoinable();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    return $this->ids;
+  }
+
+  /**
+   * Allows us to set the ids during a test.
+   */
+  public function setIds($ids) {
+    $this->ids = $ids;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields() {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function query() {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function calculateDependencies() {
+    return [];
+  }
+
+}

core/modules/migrate/tests/src/Unit/TestMigrateExecutable.php

@@ -0,0 +1,251 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\TestMigrateExecutable.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\migrate\MigrateExecutable;
+
+/**
+ * Tests MigrateExecutable.
+ */
+class TestMigrateExecutable extends MigrateExecutable {
+
+  /**
+   * The (fake) number of seconds elapsed since the start of the test.
+   *
+   * @var int
+   */
+  protected $timeElapsed;
+
+  /**
+   * The fake memory usage in bytes.
+   *
+   * @var int
+   */
+  protected $memoryUsage;
+
+  /**
+   * The cleared memory usage.
+   *
+   * @var int
+   */
+  protected $clearedMemoryUsage;
+
+  /**
+   * Sets the string translation service.
+   *
+   * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
+   *   The translation manager.
+   */
+  public function setStringTranslation(TranslationInterface $string_translation) {
+    $this->stringTranslation = $string_translation;
+  }
+
+  /**
+   * Allows access to protected timeOptionExceeded method.
+   *
+   * @return bool
+   *   A threshold exceeded value.
+   */
+  public function timeOptionExceeded() {
+    return parent::timeOptionExceeded();
+  }
+
+  /**
+   * Allows access to set protected maxExecTime property.
+   *
+   * @param int $max_exec_time
+   *   The value to set.
+   */
+  public function setMaxExecTime($max_exec_time) {
+    $this->maxExecTime = $max_exec_time;
+  }
+
+  /**
+   * Allows access to protected maxExecTime property.
+   *
+   * @return int
+   *   The value of the protected property.
+   */
+  public function getMaxExecTime() {
+    return $this->maxExecTime;
+  }
+
+  /**
+   * Allows access to protected successesSinceFeedback property.
+   *
+   * @return int
+   *   The value of the protected property.
+   */
+  public function getSuccessesSinceFeedback() {
+    return $this->successesSinceFeedback;
+  }
+
+  /**
+   * Allows access to protected totalSuccesses property.
+   *
+   * @return int
+   *   The value of the protected property.
+   */
+  public function getTotalSuccesses() {
+    return $this->totalSuccesses;
+  }
+
+  /**
+   * Allows access to protected totalProcessed property.
+   *
+   * @return int
+   *   The value of the protected property.
+   */
+  public function getTotalProcessed() {
+    return $this->totalProcessed;
+  }
+
+  /**
+   * Allows access to protected processedSinceFeedback property.
+   *
+   * @return int
+   *   The value of the protected property.
+   */
+  public function getProcessedSinceFeedback() {
+    return $this->processedSinceFeedback;
+  }
+
+  /**
+   * Allows access to protected maxExecTimeExceeded method.
+   *
+   * @return bool
+   *   The threshold exceeded value.
+   */
+  public function maxExecTimeExceeded() {
+    return parent::maxExecTimeExceeded();
+  }
+
+  /**
+   * Allows access to set protected source property.
+   *
+   * @param \Drupal\migrate\Plugin\MigrateSourceInterface $source
+   *   The value to set.
+   */
+  public function setSource($source) {
+    $this->source = $source;
+  }
+
+  /**
+   * Allows access to protected sourceIdValues property.
+   *
+   * @param array $source_id_values
+   *   The value to set.
+   */
+  public function setSourceIdValues($source_id_values) {
+    $this->sourceIdValues = $source_id_values;
+  }
+
+  /**
+   * Allows setting a fake elapsed time.
+   *
+   * @param int $time
+   *   The time in seconds.
+   */
+  public function setTimeElapsed($time) {
+    $this->timeElapsed = $time;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getTimeElapsed() {
+    return $this->timeElapsed;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function handleException(\Exception $exception, $save = TRUE) {
+    $message = $exception->getMessage();
+    if ($save) {
+      $this->saveMessage($message);
+    }
+    $this->message->display($message);
+  }
+
+  /**
+   * Allows access to the protected memoryExceeded method.
+   *
+   * @return bool
+   *   The memoryExceeded value.
+   */
+  public function memoryExceeded() {
+    return parent::memoryExceeded();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function attemptMemoryReclaim() {
+    return $this->clearedMemoryUsage;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getMemoryUsage() {
+    return $this->memoryUsage;
+  }
+
+  /**
+   * Sets the fake memory usage.
+   *
+   * @param int $memory_usage
+   *   The fake memory usage value.
+   * @param int $cleared_memory_usage
+   *   (optional) The fake cleared memory value.
+   */
+  public function setMemoryUsage($memory_usage, $cleared_memory_usage = NULL) {
+    $this->memoryUsage = $memory_usage;
+    $this->clearedMemoryUsage = $cleared_memory_usage;
+  }
+
+  /**
+   * Sets the memory limit.
+   *
+   * @param int $memory_limit
+   *   The memory limit.
+   */
+  public function setMemoryLimit($memory_limit) {
+    $this->memoryLimit = $memory_limit;
+  }
+
+  /**
+   * Sets the memory threshold.
+   *
+   * @param float $threshold
+   *   The new threshold.
+   */
+  public function setMemoryThreshold($threshold) {
+    $this->memoryThreshold = $threshold;
+  }
+
+  /**
+   * Sets the time threshold.
+   *
+   * @param float $threshold
+   *   The new threshold.
+   */
+  public function setTimeThreshold($threshold) {
+    $this->timeThreshold = $threshold;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function formatSize($size) {
+    return $size;
+  }
+
+}

core/modules/migrate/tests/src/Unit/TestSqlIdMap.php

@@ -0,0 +1,67 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\TestSqlIdMap.
+ */
+
+namespace Drupal\Tests\migrate\Unit;
+
+use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Core\Database\Connection;
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\Plugin\migrate\id_map\Sql;
+
+/**
+ * Defines a SQL ID map for use in tests.
+ */
+class TestSqlIdMap extends Sql implements \Iterator {
+
+  /**
+   * Constructs a TestSqlIdMap object.
+   *
+   * @param \Drupal\Core\Database\Connection $database
+   *   The database.
+   * @param array $configuration
+   *   The configuration.
+   * @param string $plugin_id
+   *   The plugin ID for the migration process to do.
+   * @param mixed $plugin_definition
+   *   The configuration for the plugin.
+   * @param \Drupal\migrate\Entity\MigrationInterface $migration
+   *   The migration to do.
+   */
+  public function __construct(Connection $database, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration) {
+    $this->database = $database;
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDatabase() {
+    return parent::getDatabase();
+  }
+
+  protected function getFieldSchema(array $id_definition) {
+    if (!isset($id_definition['type'])) {
+      return array();
+    }
+    switch ($id_definition['type']) {
+      case 'integer':
+        return array(
+          'type' => 'int',
+          'not null' => TRUE,
+        );
+      case 'string':
+        return array(
+          'type' => 'varchar',
+          'length' => 255,
+          'not null' => FALSE,
+        );
+      default:
+        throw new MigrateException(SafeMarkup::format('@type not supported', array('@type' => $id_definition['type'])));
+    }
+  }
+}

core/modules/migrate/tests/src/Unit/destination/ConfigTest.php

@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\migrate\Unit\destination\ConfigTest.
+ */
+
+namespace Drupal\Tests\migrate\Unit\destination;
+
+use Drupal\migrate\Plugin\migrate\destination\Config;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\migrate\Plugin\migrate\destination\Config
+ * @group migrate
+ */
+class ConfigTest extends UnitTestCase {
+
+  /**
+   * Test the import method.
+   */
+  public function testImport() {
+    $source = array(
+      'test' => 'x',
+    );
+    $migration = $this->getMockBuilder('Drupal\migrate\Entity\Migration')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $config = $this->getMockBuilder('Drupal\Core\Config\Config')
+      ->disableOriginalConstructor()
+      ->getMock();
+    foreach ($source as $key => $val) {
+      $config->expects($this->once())
+        ->method('set')
+        ->with($this->equalTo($key), $this->equalTo($val))
+        ->will($this->returnValue($config));
+    }
+    $config->expects($this->once())
+      ->method('save');
+    $config_factory = $this->getMock('Drupal\Core\Config\ConfigFactoryInterface');
+    $config_factory->expects($this->once())
+      ->method('getEditable')
+      ->with('d8_config')
+      ->will($this->returnValue($config));
+    $row = $this->getMockBuilder('Drupal\migrate\Row')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $row->expects($this->once())
+      ->method('getRawDestination')
+      ->will($this->returnValue($source));
+    $destination = new Config(array('config_name' => 'd8_config'), 'd8_config', array('pluginId' => 'd8_config'), $migration, $config_factory);
+    $destination->import($row);
+  }
+
+}