Update to Drupal 8.0.0 beta 14. For more information, see https://drupal.org/node/2544542

core/modules/config/config.links.menu.yml

@@ -1,5 +1,5 @@
 config.sync:
-  title: 'Configuration management'
-  description: 'Import, export, or synchronize your site configuration.'
+  title: 'Configuration synchronization'
+  description: 'Import and export your configuration.'
   route_name: config.sync
   parent: system.admin_config_development

core/modules/config/config.module

@@ -15,9 +15,20 @@ function config_help($route_name, RouteMatchInterface $route_match) {
     case 'help.page.config':
       $output = '';
       $output .= '<h3>' . t('About') . '</h3>';
-      $output .= '<p>' . t('The Configuration manager module provides a user interface for importing and exporting configuration changes; i.e., for staging configuration data between multiple instances of this web site. For more information, see the online handbook entry for <a href="!url">Configuration manager module</a>', array(
-        '!url' => 'https://www.drupal.org/documentation/administer/config',
-      )) . '</p>';
+      $output .= '<p>' . t('The Configuration Manager module provides a user interface for importing and exporting configuration changes between installations of your website in different environments. Configuration is stored in YAML format. For more information, see the <a href="!url">online documentation for the Configuration Manager module</a>.', array('!url' => 'https://www.drupal.org/documentation/administer/config')) . '</p>';
+      $output .= '<h3>' . t('Uses') . '</h3>';
+      $output .= '<dl>';
+      $output .= '<dt>' . t('Exporting the full configuration') . '</dt>';
+      $output .= '<dd>' . t('You can create and download an archive consisting of all your site\'s configuration exported as <em>*.yml</em> files on the <a href="!url">Export</a> page.' , array('!url' => \Drupal::url('config.export_full'))) . '</dd>';
+      $output .= '<dt>' . t('Importing a full configuration') . '</dt>';
+      $output .= '<dd>' . t('You can upload a full site configuration from an archive file on the <a href="!url">Import</a> page. When importing data from a different environment, the site and import files must have matching configuration values for UUID in the <em>system.site</em> configuration item. That means that your other environments should initially be set up as clones of the target site. Migrations are not supported.', array('!url' => \Drupal::url('config.import_full'))) . '</dd>';
+      $output .= '<dt>' . t('Synchronizing configuration'). '</dt>';
+      $output .= '<dd>' . t('You can review differences between the active configuration and an imported configuration archive on the <a href="!synchronize">Synchronize</a> page to ensure that the changes are as expected, before finalizing the import. The Synchronize page also shows configuration items that would be added or removed.', array('!synchronize' => \Drupal::url('config.sync'))) . '</dd>';
+      $output .= '<dt>' . t('Exporting a single configuration item') . '</dt>';
+      $output .= '<dd>' . t('You can export a single configuration item by selecting a <em>Configuration type</em> and <em>Configuration name</em> on the <a href="!single-export">Single export</a> page. The configuration and its corresponding <em>*.yml file name</em> are then displayed on the page for you to copy.', array('!single-export' => \Drupal::url('config.export_single'))) . '</dd>';
+      $output .= '<dt>' . t('Importing a single configuration item') . '</dt>';
+      $output .= '<dd>' . t('You can import a single configuration item by pasting it in YAML format into the form on the <a href="!single-import">Single import</a> page.', array('!single-import' => \Drupal::url('config.import_single'))) . '</dd>';
+      $output .= '</dl>';
       return $output;
 
     case 'config.sync':
@@ -25,9 +36,24 @@ function config_help($route_name, RouteMatchInterface $route_match) {
       $output .= '<p>' . t('Import configuration that is placed in your staging directory. All changes, deletions, renames, and additions are listed below.') . '</p>';
       return $output;
 
+    case 'config.export_full':
+      $output = '';
+      $output .= '<p>' . t('The full export page can be used to export the full configuration of this site, and download it as a gzipped tar file.') . '</p>';
+      return $output;
+
     case 'config.import_full':
       $output = '';
-      $output .= '<p>' . t('After uploading a configuration archive, you will be able to examine the changes and import them.') . '</p>';
+      $output .= '<p>' . t('The full import page can be used to import a full set of configuration for this site by uploading a gzipped or bzipped tar file consisting of all configuration YAML files. The results will be placed in a the staging directory, so they can be compared in the Synchronize tab. There the import can be finalized.') . '</p>';
+      return $output;
+
+    case 'config.export_single':
+      $output = '';
+      $output .= '<p>' . t('The single export page can be used to display a single configuration item in a YAML structure.') . '</p>';
+      return $output;
+
+    case 'config.import_single':
+      $output = '';
+      $output .= '<p>' . t('The single import page can be used to import a single configuration item by pasting a YAML structure into the text field.') . '</p>';
       return $output;
   }
 }

core/modules/config/src/Tests/CacheabilityMetadataConfigOverrideIntegrationTest.php

@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config\Tests\CacheabilityMetadataConfigOverrideIntegrationTest.
+ */
+
+namespace Drupal\config\Tests;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests if configuration overrides correctly affect cacheability metadata.
+ *
+ * @group config
+ */
+class CacheabilityMetadataConfigOverrideIntegrationTest extends WebTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = [
+    'block_test',
+    'config_override_integration_test',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+
+    // @todo If our block does not contain any content then the cache context
+    //   is not bubbling up and the test fails. Remove this line once the cache
+    //   contexts are properly set. See https://www.drupal.org/node/2529980.
+    \Drupal::state()->set('block_test.content', 'Needs to have some content');
+
+    $this->drupalLogin($this->drupalCreateUser());
+  }
+
+  /**
+   * Tests if config overrides correctly set cacheability metadata.
+   */
+  public function testConfigOverride() {
+    // Check the default (disabled) state of the cache context. The block label
+    // should not be overridden.
+    $this->drupalGet('<front>');
+    $this->assertNoText('Overridden block label');
+
+    // Both the cache context and tag should be present.
+    $this->assertCacheContext('config_override_integration_test');
+    $this->assertCacheTag('config_override_integration_test_tag');
+
+    // Flip the state of the cache context. The block label should now be
+    // overridden.
+    \Drupal::state()->set('config_override_integration_test.enabled', TRUE);
+    $this->drupalGet('<front>');
+    $this->assertText('Overridden block label');
+
+    // Both the cache context and tag should still be present.
+    $this->assertCacheContext('config_override_integration_test');
+    $this->assertCacheTag('config_override_integration_test_tag');
+  }
+
+}

core/modules/config/src/Tests/CacheabilityMetadataConfigOverrideTest.php

@@ -0,0 +1,95 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config\Tests\CacheabilityMetadataConfigOverrideTest.
+ */
+
+namespace Drupal\config\Tests;
+
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\config_override_test\Cache\PirateDayCacheContext;
+use Drupal\simpletest\KernelTestBase;
+
+/**
+ * Tests if configuration overrides correctly affect cacheability metadata.
+ *
+ * @group config
+ */
+class CacheabilityMetadataConfigOverrideTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = [
+    'block',
+    'block_content',
+    'config',
+    'config_override_test',
+    'system',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+    $this->installEntitySchema('block_content');
+    $this->installConfig(['config_override_test']);
+  }
+
+  /**
+   * Tests if config overrides correctly set cacheability metadata.
+   */
+  public function testConfigOverride() {
+    // It's pirate day today!
+    $GLOBALS['it_is_pirate_day'] = TRUE;
+
+    $config_factory = $this->container->get('config.factory');
+    $config = $config_factory->get('system.theme');
+
+    // Check that we are using the Pirate theme.
+    $theme = $config->get('default');
+    $this->assertEqual('pirate', $theme);
+
+    // Check that the cacheability metadata is correct.
+    $this->assertEqual(['pirate_day'], $config->getCacheContexts());
+    $this->assertEqual(['config:system.theme', 'pirate-day-tag'], $config->getCacheTags());
+    $this->assertEqual(PirateDayCacheContext::PIRATE_DAY_MAX_AGE, $config->getCacheMaxAge());
+  }
+
+  /**
+   * Tests if config overrides set cacheability metadata on config entities.
+   */
+  public function testConfigEntityOverride() {
+    // It's pirate day today!
+    $GLOBALS['it_is_pirate_day'] = TRUE;
+
+    // Load the User login block and check that its cacheability metadata is
+    // overridden correctly. This verifies that the metadata is correctly
+    // applied to config entities.
+    /** @var EntityManagerInterface $entity_manager */
+    $entity_manager = $this->container->get('entity.manager');
+    $block = $entity_manager->getStorage('block')->load('call_to_action');
+
+    // Check that our call to action message is appealing to filibusters.
+    $this->assertEqual($block->label(), 'Draw yer cutlasses!');
+
+    // Check that the cacheability metadata is correct.
+    $this->assertEqual(['pirate_day'], $block->getCacheContexts());
+    $this->assertEqual(['config:block.block.call_to_action', 'pirate-day-tag'], $block->getCacheTags());
+    $this->assertEqual(PirateDayCacheContext::PIRATE_DAY_MAX_AGE, $block->getCacheMaxAge());
+
+    // Check that duplicating a config entity does not have the original config
+    // entity's cache tag.
+    $this->assertEqual(['config:block.block.', 'pirate-day-tag'], $block->createDuplicate()->getCacheTags());
+
+    // Check that renaming a config entity does not have the original config
+    // entity's cache tag.
+    $block->set('id', 'call_to_looting')->save();
+    $this->assertEqual(['pirate_day'], $block->getCacheContexts());
+    $this->assertEqual(['config:block.block.call_to_looting', 'pirate-day-tag'], $block->getCacheTags());
+    $this->assertEqual(PirateDayCacheContext::PIRATE_DAY_MAX_AGE, $block->getCacheMaxAge());
+  }
+
+}

core/modules/config/src/Tests/ConfigEntityFormOverrideTest.php

@@ -31,6 +31,8 @@ class ConfigEntityFormOverrideTest extends WebTestBase {
     $overridden_label = 'Overridden label';
     $edited_label = 'Edited label';
 
+    $config_test_storage = $this->container->get('entity.manager')->getStorage('config_test');
+
     // Set up an override.
     $settings['config']['config_test.dynamic.dotted.default']['label'] = (object) array(
       'value' => $overridden_label,
@@ -39,7 +41,7 @@ class ConfigEntityFormOverrideTest extends WebTestBase {
     $this->writeSettings($settings);
 
     // Test that the overridden label is loaded with the entity.
-    $this->assertEqual(config_test_load('dotted.default')->label(), $overridden_label);
+    $this->assertEqual($config_test_storage->load('dotted.default')->label(), $overridden_label);
 
     // Test that the original label on the listing page is intact.
     $this->drupalGet('admin/structure/config_test');
@@ -67,7 +69,7 @@ class ConfigEntityFormOverrideTest extends WebTestBase {
     $this->assertIdentical((string) $elements[0]['value'], $edited_label);
 
     // Test that the overridden label is still loaded with the entity.
-    $this->assertEqual(config_test_load('dotted.default')->label(), $overridden_label);
+    $this->assertEqual($config_test_storage->load('dotted.default')->label(), $overridden_label);
   }
 
 }

core/modules/config/src/Tests/ConfigImporterTest.php

@@ -295,8 +295,8 @@ class ConfigImporterTest extends KernelTestBase {
 
     $logs = $this->configImporter->getErrors();
     $this->assertEqual(count($logs), 1);
-    $message = SafeMarkup::format('config_test entity with ID @name already exists', array('@name' => 'secondary'));
-    $this->assertEqual($logs[0], SafeMarkup::format('Unexpected error during import with operation @op for @name: @message.', array('@op' => 'create', '@name' => $name_primary, '@message' => $message)));
+    $message = SafeMarkup::format("'config_test' entity with ID '@name' already exists", array('@name' => 'secondary'));
+    $this->assertEqual($logs[0], SafeMarkup::format('Unexpected error during import with operation @op for @name: !message.', array('@op' => 'create', '@name' => $name_primary, '!message' => $message)));
   }
 
   /**

core/modules/config/src/Tests/ConfigInstallWebTest.php

@@ -127,7 +127,7 @@ class ConfigInstallWebTest extends WebTestBase {
     // will install the config_test module first because it is a dependency of
     // config_install_fail_test.
     // @see \Drupal\system\Form\ModulesListForm::submitForm()
-    $this->drupalPostForm('admin/modules', array('modules[Testing][config_test][enable]' => TRUE, 'modules[Testing][config_install_fail_test][enable]' => TRUE), t('Save configuration'));
+    $this->drupalPostForm('admin/modules', array('modules[Testing][config_test][enable]' => TRUE, 'modules[Testing][config_install_fail_test][enable]' => TRUE), t('Install'));
     $this->assertRaw('Unable to install Configuration install fail test, <em class="placeholder">config_test.dynamic.dotted.default</em> already exists in active configuration.');
 
     // Uninstall the config_test module to test the confirm form.
@@ -138,7 +138,7 @@ class ConfigInstallWebTest extends WebTestBase {
     // The user is shown a confirm form because the config_test module is a
     // dependency.
     // @see \Drupal\system\Form\ModulesListConfirmForm::submitForm()
-    $this->drupalPostForm('admin/modules', array('modules[Testing][config_install_fail_test][enable]' => TRUE), t('Save configuration'));
+    $this->drupalPostForm('admin/modules', array('modules[Testing][config_install_fail_test][enable]' => TRUE), t('Install'));
     $this->drupalPostForm(NULL, array(), t('Continue'));
     $this->assertRaw('Unable to install Configuration install fail test, <em class="placeholder">config_test.dynamic.dotted.default</em> already exists in active configuration.');
 
@@ -152,7 +152,7 @@ class ConfigInstallWebTest extends WebTestBase {
       ->set('label', 'Je suis Charlie')
       ->save();
 
-    $this->drupalPostForm('admin/modules', array('modules[Testing][config_install_fail_test][enable]' => TRUE), t('Save configuration'));
+    $this->drupalPostForm('admin/modules', array('modules[Testing][config_install_fail_test][enable]' => TRUE), t('Install'));
     $this->assertRaw('Unable to install Configuration install fail test, <em class="placeholder">config_test.dynamic.dotted.default, language/fr/config_test.dynamic.dotted.default</em> already exist in active configuration.');
 
     // Test installing a theme through the UI that has existing configuration.
@@ -183,12 +183,12 @@ class ConfigInstallWebTest extends WebTestBase {
     $this->drupalLogin($this->adminUser);
     // We need to install separately since config_install_dependency_test does
     // not depend on config_test and order is important.
-    $this->drupalPostForm('admin/modules', array('modules[Testing][config_test][enable]' => TRUE), t('Save configuration'));
-    $this->drupalPostForm('admin/modules', array('modules[Testing][config_install_dependency_test][enable]' => TRUE), t('Save configuration'));
+    $this->drupalPostForm('admin/modules', array('modules[Testing][config_test][enable]' => TRUE), t('Install'));
+    $this->drupalPostForm('admin/modules', array('modules[Testing][config_install_dependency_test][enable]' => TRUE), t('Install'));
     $this->assertRaw('Unable to install Config install dependency test, <em class="placeholder">config_test.dynamic.other_module_test_with_dependency</em> has unmet dependencies.');
 
-    $this->drupalPostForm('admin/modules', array('modules[Testing][config_other_module_config_test][enable]' => TRUE), t('Save configuration'));
-    $this->drupalPostForm('admin/modules', array('modules[Testing][config_install_dependency_test][enable]' => TRUE), t('Save configuration'));
+    $this->drupalPostForm('admin/modules', array('modules[Testing][config_other_module_config_test][enable]' => TRUE), t('Install'));
+    $this->drupalPostForm('admin/modules', array('modules[Testing][config_install_dependency_test][enable]' => TRUE), t('Install'));
     $this->rebuildContainer();
     $this->assertTrue(entity_load('config_test', 'other_module_test_with_dependency'), 'The config_test.dynamic.other_module_test_with_dependency configuration has been created during install.');
   }

core/modules/config/tests/config_entity_static_cache_test/src/ConfigOverrider.php

@@ -7,6 +7,7 @@
 
 namespace Drupal\config_entity_static_cache_test;
 
+use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Config\ConfigFactoryOverrideInterface;
 use Drupal\Core\Config\StorageInterface;
 
@@ -40,4 +41,11 @@ class ConfigOverrider implements ConfigFactoryOverrideInterface {
     return NULL;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($name) {
+    return new CacheableMetadata();
+  }
+
 }

core/modules/config/tests/config_override_integration_test/config/install/block.block.config_override_test.yml

@@ -0,0 +1,24 @@
+id: config_override_test
+theme: classy
+weight: 0
+status: true
+langcode: en
+region: content
+plugin: test_cache
+settings:
+  label: 'Test HTML block'
+  provider: block_test
+  label_display: visible
+  status: true
+  info: ''
+  view_mode: default
+dependencies:
+  module:
+    - block_test
+  theme:
+    - classy
+visibility:
+  request_path:
+    id: request_path
+    pages: ''
+    negate: false

core/modules/config/tests/config_override_integration_test/config_override_integration_test.info.yml

@@ -0,0 +1,9 @@
+name: 'Configuration override integration test'
+type: module
+package: Testing
+version: VERSION
+core: 8.x
+
+dependencies:
+  - block
+  - block_test

core/modules/config/tests/config_override_integration_test/config_override_integration_test.services.yml

@@ -0,0 +1,9 @@
+services:
+  cache_context.config_override_integration_test:
+    class: Drupal\config_override_integration_test\Cache\ConfigOverrideIntegrationTestCacheContext
+    tags:
+      - { name: cache.context }
+  config_override_integration_test.config_override:
+    class: Drupal\config_override_integration_test\CacheabilityMetadataConfigOverride
+    tags:
+      - { name: config.factory.override }

core/modules/config/tests/config_override_integration_test/src/Cache/ConfigOverrideIntegrationTestCacheContext.php

@@ -0,0 +1,47 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config_override_integration_test\Cache\ConfigOverrideIntegrationTestCacheContext.
+ */
+
+namespace Drupal\config_override_integration_test\Cache;
+
+use Drupal\Core\Cache\CacheableMetadata;
+use Drupal\Core\Cache\Context\CacheContextInterface;
+
+/**
+ * A cache context service intended for the config override integration test.
+ *
+ * Cache context ID: 'config_override_integration_test'.
+ */
+class ConfigOverrideIntegrationTestCacheContext implements CacheContextInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getLabel() {
+    return t('Config override integration test');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getContext() {
+    // Default to the 'disabled' state.
+    $state = \Drupal::state()->get('config_override_integration_test.enabled', FALSE) ? 'yes' : 'no';
+    return 'config_override_integration_test.' . $state;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata() {
+    // Since this depends on State this can change at any time and is not
+    // cacheable.
+    $metadata = new CacheableMetadata();
+    $metadata->setCacheMaxAge(0);
+    return $metadata;
+  }
+
+}

core/modules/config/tests/config_override_integration_test/src/CacheabilityMetadataConfigOverride.php

@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config_override_integration_test\CacheabilityMetadataConfigOverride.
+ */
+
+namespace Drupal\config_override_integration_test;
+
+use Drupal\Core\Cache\CacheableMetadata;
+use Drupal\Core\Config\ConfigFactoryOverrideInterface;
+use Drupal\Core\Config\StorageInterface;
+
+/**
+ * Test implementation of a config override that provides cacheability metadata.
+ */
+class CacheabilityMetadataConfigOverride implements ConfigFactoryOverrideInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function loadOverrides($names) {
+    $overrides = [];
+
+    // Override the test block depending on the state set in the test.
+    $state = \Drupal::state()->get('config_override_integration_test.enabled', FALSE);
+    if (in_array('block.block.config_override_test', $names) && $state !== FALSE) {
+      $overrides = $overrides + [
+        'block.block.config_override_test' => [
+          'settings' => ['label' => 'Overridden block label'],
+        ],
+      ];
+    }
+
+    return $overrides;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheSuffix() {
+    return 'config_override_integration_test';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function createConfigObject($name, $collection = StorageInterface::DEFAULT_COLLECTION) {
+    return NULL;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($name) {
+    $metadata = new CacheableMetadata();
+    if ($name === 'block.block.config_override_test') {
+      $metadata
+        ->setCacheContexts(['config_override_integration_test'])
+        ->setCacheTags(['config_override_integration_test_tag']);
+    }
+    return $metadata;
+  }
+
+}

core/modules/config/tests/config_override_test/config/install/block.block.call_to_action.yml

@@ -0,0 +1,26 @@
+langcode: en
+status: true
+dependencies:
+  module:
+    - block_content
+  theme:
+    - classy
+id: call_to_action
+theme: classy
+region: content
+weight: null
+provider: null
+plugin: 'block_content:d7c9d8ba-663f-41b4-8756-86bc55c44653'
+settings:
+  id: 'block_content:d7c9d8ba-663f-41b4-8756-86bc55c44653'
+  label: 'Shop for cheap now!'
+  provider: block_content
+  label_display: visible
+  status: true
+  info: ''
+  view_mode: default
+visibility:
+  request_path:
+    id: request_path
+    pages: ''
+    negate: false

core/modules/config/tests/config_override_test/config_override_test.info.yml

@@ -3,3 +3,7 @@ type: module
 package: Testing
 version: VERSION
 core: 8.x
+
+dependencies:
+  - block
+  - block_content

core/modules/config/tests/config_override_test/config_override_test.services.yml

@@ -1,4 +1,8 @@
 services:
+  cache_context.pirate_day:
+    class: Drupal\config_override_test\Cache\PirateDayCacheContext
+    tags:
+      - { name: cache.context }
   config_override_test.overrider:
     class: Drupal\config_override_test\ConfigOverrider
     tags:
@@ -7,3 +11,7 @@ services:
     class: Drupal\config_override_test\ConfigOverriderLowPriority
     tags:
       - { name: config.factory.override, priority: -100 }
+  config_override_test.pirate_day_cacheability_metadata_override:
+    class: Drupal\config_override_test\PirateDayCacheabilityMetadataConfigOverride
+    tags:
+      - { name: config.factory.override }

core/modules/config/tests/config_override_test/src/Cache/PirateDayCacheContext.php

@@ -0,0 +1,66 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config_override_test\Cache\PirateDayCacheContext.
+ */
+
+namespace Drupal\config_override_test\Cache;
+
+use Drupal\Core\Cache\CacheableMetadata;
+use Drupal\Core\Cache\Context\CacheContextInterface;
+
+/**
+ * Defines the PirateDayCacheContext service that allows to cache the booty.
+ *
+ * Cache context ID: 'pirate_day'.
+ */
+class PirateDayCacheContext implements CacheContextInterface {
+
+  /**
+   * The length of Pirate Day. It lasts 24 hours.
+   *
+   * This is a simplified test implementation. In a real life Pirate Day module
+   * this data wouldn't be defined in a constant, but calculated in a static
+   * method. If it were Pirate Day it should return the number of seconds until
+   * midnight, and on all other days it should return the number of seconds
+   * until the start of the next Pirate Day.
+   */
+  const PIRATE_DAY_MAX_AGE = 86400;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getLabel() {
+    return t('Pirate day');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getContext() {
+    $is_pirate_day = static::isPirateDay() ? 'yarr' : 'nay';
+    return "pirate_day." . $is_pirate_day;
+  }
+
+  /**
+   * Returns whether or not it is Pirate Day.
+   *
+   * To ease testing this is determined with a global variable rather than using
+   * the traditional compass and sextant.
+   *
+   * @return bool
+   *   Returns TRUE if it is Pirate Day today.
+   */
+  public static function isPirateDay() {
+    return !empty($GLOBALS['it_is_pirate_day']);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata() {
+    return new CacheableMetadata();
+  }
+
+}

core/modules/config/tests/config_override_test/src/ConfigOverrider.php

@@ -7,6 +7,7 @@
 
 namespace Drupal\config_override_test;
 
+use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Config\ConfigFactoryOverrideInterface;
 
 /**
@@ -44,5 +45,11 @@ class ConfigOverrider implements ConfigFactoryOverrideInterface {
     return NULL;
   }
 
-}
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($name) {
+    return new CacheableMetadata();
+  }
 
+}

core/modules/config/tests/config_override_test/src/ConfigOverriderLowPriority.php

@@ -7,6 +7,7 @@
 
 namespace Drupal\config_override_test;
 
+use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Config\ConfigFactoryOverrideInterface;
 use Drupal\Core\Config\StorageInterface;
 
@@ -49,5 +50,11 @@ class ConfigOverriderLowPriority implements ConfigFactoryOverrideInterface {
     return NULL;
   }
 
-}
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($name) {
+    return new CacheableMetadata();
+  }
 
+}

core/modules/config/tests/config_override_test/src/PirateDayCacheabilityMetadataConfigOverride.php

@@ -0,0 +1,82 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config_override_test\PirateDayCacheabilityMetadataConfigOverride.
+ */
+
+namespace Drupal\config_override_test;
+
+use Drupal\config_override_test\Cache\PirateDayCacheContext;
+use Drupal\Core\Cache\CacheableMetadata;
+use Drupal\Core\Config\ConfigFactoryOverrideInterface;
+use Drupal\Core\Config\StorageInterface;
+
+/**
+ * Test implementation of a config override that provides cacheability metadata.
+ */
+class PirateDayCacheabilityMetadataConfigOverride implements ConfigFactoryOverrideInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function loadOverrides($names) {
+    $overrides = [];
+
+    // Override the theme and the 'call_to_action' block on Pirate Day.
+    if (PirateDayCacheContext::isPirateDay()) {
+      if (in_array('system.theme', $names)) {
+        $overrides = $overrides + ['system.theme' => ['default' => 'pirate']];
+      }
+      if (in_array('block.block.call_to_action', $names)) {
+        $overrides = $overrides + [
+          'block.block.call_to_action' => [
+            'settings' => ['label' => 'Draw yer cutlasses!'],
+          ],
+        ];
+      }
+    }
+
+    return $overrides;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheSuffix() {
+    return 'PirateDayConfigOverrider';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function createConfigObject($name, $collection = StorageInterface::DEFAULT_COLLECTION) {
+    return NULL;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($name) {
+    $metadata = new CacheableMetadata();
+    $metadata
+      ->setCacheContexts(['pirate_day'])
+      ->setCacheTags(['pirate-day-tag'])
+      ->setCacheMaxAge(PirateDayCacheContext::PIRATE_DAY_MAX_AGE);
+    return $metadata;
+  }
+
+  /**
+   * Returns whether or not our overrides are potentially applicable.
+   *
+   * @param string $name
+   *   The name of the config object that is being constructed.
+   *
+   * @return bool
+   *   TRUE if the merchant ship will be boarded. FALSE if we drink rum instead.
+   */
+  protected function isCacheabilityMetadataApplicable($name) {
+    return in_array($name, ['system.theme', 'block.block.call_to_action']);
+  }
+
+}

core/modules/config/tests/config_test/config_test.module

@@ -10,16 +10,6 @@ use Symfony\Component\HttpFoundation\RedirectResponse;
 
 require_once dirname(__FILE__) . '/config_test.hooks.inc';
 
-/**
- * Loads a ConfigTest object.
- *
- * @param string $id
- *   The ID of the ConfigTest object to load.
- */
-function config_test_load($id) {
-  return entity_load('config_test', $id);
-}
-
 /**
  * Implements hook_cache_flush().
  */

core/modules/config/tests/config_test/src/ConfigTestForm.php

@@ -8,13 +8,41 @@
 namespace Drupal\config_test;
 
 use Drupal\Core\Entity\EntityForm;
+use Drupal\Core\Entity\Query\QueryFactory;
 use Drupal\Core\Form\FormStateInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Form controller for the test config edit forms.
  */
 class ConfigTestForm extends EntityForm {
 
+  /**
+   * The entity query.
+   *
+   * @var \Drupal\Core\Entity\Query\QueryFactory
+   */
+  protected $entityQuery;
+
+  /**
+   * Constructs a new ConfigTestForm.
+   *
+   * @param \Drupal\Core\Entity\Query\QueryFactory $entity_query
+   *   The entity query.
+   */
+  public function __construct(QueryFactory $entity_query) {
+    $this->entityQuery = $entity_query;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('entity.query')
+    );
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -33,7 +61,7 @@ class ConfigTestForm extends EntityForm {
       '#default_value' => $entity->id(),
       '#required' => TRUE,
       '#machine_name' => array(
-        'exists' => 'config_test_load',
+        'exists' => [$this, 'exists'],
         'replace_pattern' => '[^a-z0-9_.]+',
       ),
     );
@@ -142,4 +170,25 @@ class ConfigTestForm extends EntityForm {
     $form_state->setRedirectUrl($this->entity->urlInfo('collection'));
   }
 
+  /**
+   * Determines if the entity already exists.
+   *
+   * @param string|int $entity_id
+   *   The entity ID.
+   * @param array $element
+   *   The form element.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
+   *
+   * @return bool
+   *   TRUE if the entity exists, FALSE otherwise.
+   */
+  public function exists($entity_id, array $element, FormStateInterface $form_state) {
+    /** @var \Drupal\Core\Config\Entity\ConfigEntityInterface $entity */
+    $entity = $form_state->getFormObject()->getEntity();
+    return (bool) $this->entityQuery->get($entity->getEntityTypeId())
+      ->condition($entity->getEntityType()->getKey('id'), $entity_id)
+      ->execute();
+  }
+
 }