Move into nested docroot

web/core/modules/forum/config/install/forum.settings.yml

@@ -0,0 +1,10 @@
+block:
+  active:
+    limit: 5
+  new:
+    limit: 5
+topics:
+  hot_threshold: 15
+  order: 1
+  page_limit: 25
+vocabulary: forums

web/core/modules/forum/config/optional/comment.type.comment_forum.yml

@@ -0,0 +1,10 @@
+langcode: en
+status: true
+dependencies:
+  enforced:
+    module:
+      - forum
+id: comment_forum
+label: Comment_forum
+target_entity_type_id: node
+description: 'Default comment field'

web/core/modules/forum/config/optional/core.base_field_override.node.forum.promote.yml

@@ -0,0 +1,21 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - node.type.forum
+id: node.forum.promote
+field_name: promote
+entity_type: node
+bundle: forum
+label: 'Promoted to front page'
+description: ''
+required: false
+translatable: true
+default_value:
+  -
+    value: 0
+default_value_callback: ''
+settings:
+  on_label: 'On'
+  off_label: 'Off'
+field_type: boolean

web/core/modules/forum/config/optional/core.base_field_override.node.forum.title.yml

@@ -0,0 +1,17 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - node.type.forum
+id: node.forum.title
+field_name: title
+entity_type: node
+bundle: forum
+label: Subject
+description: ''
+required: true
+translatable: true
+default_value: {  }
+default_value_callback: ''
+settings: {  }
+field_type: string

web/core/modules/forum/config/optional/core.entity_form_display.comment.comment_forum.default.yml

@@ -0,0 +1,30 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - comment.type.comment_forum
+    - field.field.comment.comment_forum.comment_body
+  module:
+    - text
+id: comment.comment_forum.default
+targetEntityType: comment
+bundle: comment_forum
+mode: default
+content:
+  author:
+    weight: -2
+  comment_body:
+    type: text_textarea
+    weight: 11
+    settings:
+      rows: 5
+      placeholder: ''
+    third_party_settings: {  }
+  subject:
+    type: string_textfield
+    weight: 10
+    settings:
+      size: 60
+      placeholder: ''
+    third_party_settings: {  }
+hidden: {  }

web/core/modules/forum/config/optional/core.entity_form_display.node.forum.default.yml

@@ -0,0 +1,67 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.field.node.forum.body
+    - field.field.node.forum.comment_forum
+    - field.field.node.forum.taxonomy_forums
+    - node.type.forum
+  module:
+    - comment
+    - text
+id: node.forum.default
+targetEntityType: node
+bundle: forum
+mode: default
+content:
+  body:
+    type: text_textarea_with_summary
+    weight: 27
+    settings:
+      rows: 9
+      summary_rows: 3
+      placeholder: ''
+    third_party_settings: {  }
+  comment_forum:
+    type: comment_default
+    weight: 20
+    settings: {  }
+    third_party_settings: {  }
+  created:
+    type: datetime_timestamp
+    weight: 10
+    settings: {  }
+    third_party_settings: {  }
+  promote:
+    type: boolean_checkbox
+    settings:
+      display_label: true
+    weight: 15
+    third_party_settings: {  }
+  sticky:
+    type: boolean_checkbox
+    settings:
+      display_label: true
+    weight: 16
+    third_party_settings: {  }
+  taxonomy_forums:
+    type: options_select
+    weight: 26
+    settings: {  }
+    third_party_settings: {  }
+  title:
+    type: string_textfield
+    weight: -5
+    settings:
+      size: 60
+      placeholder: ''
+    third_party_settings: {  }
+  uid:
+    type: entity_reference_autocomplete
+    weight: 5
+    settings:
+      match_operator: CONTAINS
+      size: 60
+      placeholder: ''
+    third_party_settings: {  }
+hidden: {  }

web/core/modules/forum/config/optional/core.entity_form_display.taxonomy_term.forums.default.yml

@@ -0,0 +1,27 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.field.taxonomy_term.forums.forum_container
+    - taxonomy.vocabulary.forums
+  module:
+    - text
+id: taxonomy_term.forums.default
+targetEntityType: taxonomy_term
+bundle: forums
+mode: default
+content:
+  description:
+    type: text_textfield
+    weight: 0
+    settings: {  }
+    third_party_settings: {  }
+  name:
+    type: string_textfield
+    weight: -5
+    settings:
+      size: 60
+      placeholder: ''
+    third_party_settings: {  }
+hidden:
+  forum_container: true

web/core/modules/forum/config/optional/core.entity_view_display.comment.comment_forum.default.yml

@@ -0,0 +1,22 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - comment.type.comment_forum
+    - field.field.comment.comment_forum.comment_body
+  module:
+    - text
+id: comment.comment_forum.default
+targetEntityType: comment
+bundle: comment_forum
+mode: default
+content:
+  comment_body:
+    label: hidden
+    type: text_default
+    weight: 0
+    settings: {  }
+    third_party_settings: {  }
+  links:
+    weight: 100
+hidden: {  }

web/core/modules/forum/config/optional/core.entity_view_display.node.forum.default.yml

@@ -0,0 +1,42 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - core.entity_view_display.comment.comment_forum.default
+    - field.field.node.forum.body
+    - field.field.node.forum.comment_forum
+    - field.field.node.forum.taxonomy_forums
+    - node.type.forum
+  module:
+    - comment
+    - text
+    - user
+id: node.forum.default
+targetEntityType: node
+bundle: forum
+mode: default
+content:
+  body:
+    label: hidden
+    type: text_default
+    weight: 0
+    settings: {  }
+    third_party_settings: {  }
+  comment_forum:
+    label: hidden
+    type: comment_default
+    weight: 20
+    settings:
+      view_mode: default
+      pager_id: 0
+    third_party_settings: {  }
+  links:
+    weight: 100
+  taxonomy_forums:
+    type: entity_reference_label
+    weight: -1
+    label: above
+    settings:
+      link: true
+    third_party_settings: {  }
+hidden: {  }

web/core/modules/forum/config/optional/core.entity_view_display.node.forum.teaser.yml

@@ -0,0 +1,35 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - core.entity_view_mode.node.teaser
+    - field.field.node.forum.body
+    - field.field.node.forum.comment_forum
+    - field.field.node.forum.taxonomy_forums
+    - node.type.forum
+  module:
+    - text
+    - user
+id: node.forum.teaser
+targetEntityType: node
+bundle: forum
+mode: teaser
+content:
+  body:
+    label: hidden
+    type: text_summary_or_trimmed
+    weight: 100
+    settings:
+      trim_length: 600
+    third_party_settings: {  }
+  links:
+    weight: 101
+  taxonomy_forums:
+    type: entity_reference_label
+    weight: 10
+    label: above
+    settings:
+      link: true
+    third_party_settings: {  }
+hidden:
+  comment_forum: true

web/core/modules/forum/config/optional/core.entity_view_display.taxonomy_term.forums.default.yml

@@ -0,0 +1,21 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.field.taxonomy_term.forums.forum_container
+    - taxonomy.vocabulary.forums
+  module:
+    - text
+id: taxonomy_term.forums.default
+targetEntityType: taxonomy_term
+bundle: forums
+mode: default
+content:
+  description:
+    type: text_default
+    weight: 0
+    settings: {  }
+    third_party_settings: {  }
+    label: above
+hidden:
+  forum_container: true

web/core/modules/forum/config/optional/field.field.comment.comment_forum.comment_body.yml

@@ -0,0 +1,20 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - comment.type.comment_forum
+    - field.storage.comment.comment_body
+  module:
+    - text
+id: comment.comment_forum.comment_body
+field_name: comment_body
+entity_type: comment
+bundle: comment_forum
+label: Comment
+description: ''
+required: true
+translatable: true
+default_value: {  }
+default_value_callback: ''
+settings: {  }
+field_type: text_long

web/core/modules/forum/config/optional/field.field.node.forum.body.yml

@@ -0,0 +1,21 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.storage.node.body
+    - node.type.forum
+  module:
+    - text
+id: node.forum.body
+field_name: body
+entity_type: node
+bundle: forum
+label: Body
+description: ''
+required: false
+translatable: true
+default_value: {  }
+default_value_callback: ''
+settings:
+  display_summary: true
+field_type: text_with_summary

web/core/modules/forum/config/optional/field.field.node.forum.comment_forum.yml

@@ -0,0 +1,32 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.storage.node.comment_forum
+    - node.type.forum
+  module:
+    - comment
+id: node.forum.comment_forum
+field_name: comment_forum
+entity_type: node
+bundle: forum
+label: Comments
+description: ''
+required: true
+translatable: true
+default_value:
+  -
+    status: 2
+    cid: 0
+    last_comment_name: null
+    last_comment_timestamp: 0
+    last_comment_uid: 0
+    comment_count: 0
+default_value_callback: ''
+settings:
+  default_mode: 0
+  per_page: 50
+  form_location: true
+  anonymous: 0
+  preview: 1
+field_type: comment

web/core/modules/forum/config/optional/field.field.node.forum.taxonomy_forums.yml

@@ -0,0 +1,26 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.storage.node.taxonomy_forums
+    - node.type.forum
+    - taxonomy.vocabulary.forums
+id: node.forum.taxonomy_forums
+field_name: taxonomy_forums
+entity_type: node
+bundle: forum
+label: Forums
+description: ''
+required: true
+translatable: true
+default_value: {  }
+default_value_callback: ''
+settings:
+  handler: 'default:taxonomy_term'
+  handler_settings:
+    target_bundles:
+      forums: forums
+    sort:
+      field: _none
+    auto_create: true
+field_type: entity_reference

web/core/modules/forum/config/optional/field.field.taxonomy_term.forums.forum_container.yml

@@ -0,0 +1,22 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.storage.taxonomy_term.forum_container
+    - taxonomy.vocabulary.forums
+id: taxonomy_term.forums.forum_container
+field_name: forum_container
+entity_type: taxonomy_term
+bundle: forums
+label: Container
+description: ''
+required: true
+translatable: true
+default_value:
+  -
+    value: 0
+default_value_callback: ''
+settings:
+  on_label: 'Yes'
+  off_label: 'No'
+field_type: boolean

web/core/modules/forum/config/optional/field.storage.node.comment_forum.yml

@@ -0,0 +1,19 @@
+langcode: en
+status: true
+dependencies:
+  module:
+    - comment
+    - node
+id: node.comment_forum
+field_name: comment_forum
+entity_type: node
+type: comment
+settings:
+  comment_type: comment_forum
+module: comment
+locked: false
+cardinality: 1
+translatable: true
+indexes: {  }
+persist_with_no_fields: false
+custom_storage: false

web/core/modules/forum/config/optional/field.storage.node.taxonomy_forums.yml

@@ -0,0 +1,19 @@
+langcode: en
+status: true
+dependencies:
+  module:
+    - node
+    - taxonomy
+id: node.taxonomy_forums
+field_name: taxonomy_forums
+entity_type: node
+type: entity_reference
+settings:
+  target_type: taxonomy_term
+module: core
+locked: false
+cardinality: 1
+translatable: true
+indexes: {  }
+persist_with_no_fields: false
+custom_storage: false

web/core/modules/forum/config/optional/field.storage.taxonomy_term.forum_container.yml

@@ -0,0 +1,17 @@
+langcode: en
+status: true
+dependencies:
+  module:
+    - taxonomy
+id: taxonomy_term.forum_container
+field_name: forum_container
+entity_type: taxonomy_term
+type: boolean
+settings: {  }
+module: core
+locked: true
+cardinality: 1
+translatable: false
+indexes: {  }
+persist_with_no_fields: false
+custom_storage: false

web/core/modules/forum/config/optional/node.type.forum.yml

@@ -0,0 +1,13 @@
+langcode: en
+status: true
+dependencies:
+  enforced:
+    module:
+      - forum
+name: 'Forum topic'
+type: forum
+description: 'A <em>forum topic</em> starts a new discussion thread within a forum.'
+help: ''
+new_revision: false
+preview_mode: 1
+display_submitted: true

web/core/modules/forum/config/optional/rdf.mapping.node.forum.yml

@@ -0,0 +1,40 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - node.type.forum
+  module:
+    - node
+id: node.forum
+targetEntityType: node
+bundle: forum
+types:
+  - 'schema:Discussion'
+fieldMappings:
+  title:
+    properties:
+      - 'schema:name'
+  created:
+    properties:
+      - 'schema:dateCreated'
+    datatype_callback:
+      callable: 'Drupal\rdf\CommonDataConverter::dateIso8601Value'
+  changed:
+    properties:
+      - 'schema:dateModified'
+    datatype_callback:
+      callable: 'Drupal\rdf\CommonDataConverter::dateIso8601Value'
+  body:
+    properties:
+      - 'schema:text'
+  uid:
+    properties:
+      - 'schema:author'
+    mapping_type: rel
+  comment_count:
+    properties:
+      - 'schema:interactionCount'
+    datatype_callback:
+      callable: 'Drupal\rdf\SchemaOrgDataConverter::interactionCount'
+      arguments:
+        interaction_type: UserComments

web/core/modules/forum/config/optional/rdf.mapping.taxonomy_term.forums.yml

@@ -0,0 +1,20 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - taxonomy.vocabulary.forums
+  module:
+    - taxonomy
+id: taxonomy_term.forums
+targetEntityType: taxonomy_term
+bundle: forums
+types:
+  - 'sioc:Container'
+  - 'sioc:Forum'
+fieldMappings:
+  name:
+    properties:
+      - 'schema:name'
+  description:
+    properties:
+      - 'schema:description'

web/core/modules/forum/config/optional/taxonomy.vocabulary.forums.yml

@@ -0,0 +1,11 @@
+langcode: en
+status: true
+dependencies:
+  enforced:
+    module:
+      - forum
+name: Forums
+vid: forums
+description: 'Forum navigation vocabulary'
+hierarchy: 1
+weight: -10

web/core/modules/forum/config/schema/forum.schema.yml

@@ -0,0 +1,66 @@
+# Schema for the configuration files of the Forum module.
+
+forum.settings:
+  type: config_object
+  label: 'Forum settings'
+  mapping:
+    block:
+      type: mapping
+      label: 'Forum blocks'
+      mapping:
+        active:
+          type: mapping
+          label: 'Active forum block'
+          mapping:
+            limit:
+              type: integer
+              label: 'Active forum Count'
+        new:
+          type: mapping
+          label: 'New forum topics'
+          mapping:
+            limit:
+              type: integer
+              label: 'New forum Count'
+    topics:
+      type: mapping
+      label: 'Forum topics block'
+      mapping:
+        hot_threshold:
+          type: integer
+          label: 'Hot topic threshold'
+        order:
+          type: integer
+          label: 'Forum default topic order'
+        page_limit:
+          type: integer
+          label: 'Topics per page'
+    vocabulary:
+      type: string
+      label: 'Forum vocabulary ID'
+
+block.settings.forum_active_block:
+  type: block_settings
+  label: 'Active forum topics block'
+  mapping:
+    properties:
+      type: sequence
+      label: 'Properties'
+      sequence:
+        type: string
+    block_count:
+      type: integer
+      label: 'Block count'
+
+block.settings.forum_new_block:
+  type: block_settings
+  label: 'New forum topics block'
+  mapping:
+    properties:
+      type: sequence
+      label: 'Properties'
+      sequence:
+        type: string
+    block_count:
+      type: integer
+      label: 'Block count'

web/core/modules/forum/forum.info.yml

@@ -0,0 +1,13 @@
+name: Forum
+type: module
+description: 'Provides discussion forums.'
+dependencies:
+  - node
+  - history
+  - taxonomy
+  - comment
+  - options
+package: Core
+version: VERSION
+core: 8.x
+configure: forum.overview

web/core/modules/forum/forum.install

@@ -0,0 +1,177 @@
+<?php
+
+/**
+ * @file
+ * Install, update, and uninstall functions for the Forum module.
+ */
+
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\taxonomy\Entity\Term;
+
+/**
+ * Implements hook_install().
+ */
+function forum_install() {
+  // Set the weight of the forum.module to 1 so it is loaded after the taxonomy.module.
+  module_set_weight('forum', 1);
+  // Do not allow to delete the forum's node type machine name.
+  $locked = \Drupal::state()->get('node.type.locked');
+  $locked['forum'] = 'forum';
+  \Drupal::state()->set('node.type.locked', $locked);
+
+  if (!\Drupal::service('config.installer')->isSyncing()) {
+    // Create a default forum so forum posts can be created.
+    $term = Term::create(array(
+      'name' => t('General discussion'),
+      'description' => '',
+      'parent' => array(0),
+      'vid' => 'forums',
+      'forum_container' => 0,
+    ));
+    $term->save();
+  }
+}
+
+/**
+ * Implements hook_uninstall().
+ */
+function forum_uninstall() {
+  if ($field_storage = FieldStorageConfig::loadByName('node', 'taxonomy_forums')) {
+    $field_storage->delete();
+  }
+
+  if ($field_storage = FieldStorageConfig::loadByName('node', 'comment_forum')) {
+    $field_storage->delete();
+  }
+
+  if ($field_storage = FieldStorageConfig::loadByName('taxonomy_term', 'forum_container')) {
+    $field_storage->delete();
+  }
+
+  // Purge field data now to allow taxonomy and options module to be uninstalled
+  // if this is the only field remaining.
+  field_purge_batch(10);
+  // Allow to delete a forum's node type.
+  $locked = \Drupal::state()->get('node.type.locked');
+  unset($locked['forum']);
+  \Drupal::state()->set('node.type.locked', $locked);
+}
+
+/**
+ * Implements hook_schema().
+ */
+function forum_schema() {
+  $schema['forum'] = array(
+    'description' => 'Stores the relationship of nodes to forum terms.',
+    'fields' => array(
+      'nid' => array(
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'The {node}.nid of the node.',
+      ),
+      'vid' => array(
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'Primary Key: The {node}.vid of the node.',
+      ),
+      'tid' => array(
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'The {taxonomy_term_data}.tid of the forum term assigned to the node.',
+      ),
+    ),
+    'indexes' => array(
+      'forum_topic' => array('nid', 'tid'),
+      'tid' => array('tid'),
+    ),
+    'primary key' => array('vid'),
+    'foreign keys' => array(
+      'forum_node' => array(
+        'table' => 'node',
+        'columns' => array(
+          'nid' => 'nid',
+          'vid' => 'vid',
+        ),
+      ),
+    ),
+  );
+
+  $schema['forum_index'] = array(
+    'description' => 'Maintains denormalized information about node/term relationships.',
+    'fields' => array(
+      'nid' => array(
+        'description' => 'The {node}.nid this record tracks.',
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+      ),
+      'title' => array(
+        'description' => 'The node title.',
+        'type' => 'varchar',
+        'length' => 255,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'tid' => array(
+         'description' => 'The term ID.',
+         'type' => 'int',
+         'unsigned' => TRUE,
+         'not null' => TRUE,
+         'default' => 0,
+      ),
+      'sticky' => array(
+        'description' => 'Boolean indicating whether the node is sticky.',
+        'type' => 'int',
+        'not null' => FALSE,
+        'default' => 0,
+        'size' => 'tiny',
+      ),
+      'created' => array(
+        'description' => 'The Unix timestamp when the node was created.',
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+      ),
+      'last_comment_timestamp' => array(
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'The Unix timestamp of the last comment that was posted within this node, from {comment}.timestamp.',
+      ),
+      'comment_count' => array(
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'The total number of comments on this node.',
+      ),
+    ),
+    'indexes' => array(
+      'forum_topics' => array('nid', 'tid', 'sticky', 'last_comment_timestamp'),
+      'created' => array('created'),
+      'last_comment_timestamp' => array('last_comment_timestamp'),
+    ),
+    'foreign keys' => array(
+      'tracked_node' => array(
+        'table' => 'node',
+        'columns' => array('nid' => 'nid'),
+      ),
+      'term' => array(
+        'table' => 'taxonomy_term_data',
+        'columns' => array(
+          'tid' => 'tid',
+        ),
+      ),
+    ),
+  );
+
+  return $schema;
+}

web/core/modules/forum/forum.links.action.yml

@@ -0,0 +1,11 @@
+forum_add_forum_local_action:
+  route_name: forum.add_forum
+  title: 'Add forum'
+  appears_on:
+    - forum.overview
+
+forum_add_container_local_action:
+  route_name: forum.add_container
+  title: 'Add container'
+  appears_on:
+    - forum.overview

web/core/modules/forum/forum.links.menu.yml

@@ -0,0 +1,9 @@
+forum.index:
+  title: Forums
+  route_name: forum.index
+  menu_name: tools
+forum.overview:
+  title: Forums
+  parent: system.admin_structure
+  description: 'Control forum hierarchy settings.'
+  route_name: forum.overview

web/core/modules/forum/forum.links.task.yml

@@ -0,0 +1,9 @@
+forum.overview:
+  route_name: forum.overview
+  base_route: forum.overview
+  title: List
+forum.settings:
+  route_name: forum.settings
+  base_route: forum.overview
+  title: Settings
+  weight: 100

web/core/modules/forum/forum.module

@@ -0,0 +1,642 @@
+<?php
+
+/**
+ * @file
+ * Provides discussion forums.
+ */
+
+use Drupal\comment\CommentInterface;
+use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Url;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\taxonomy\VocabularyInterface;
+use Drupal\user\Entity\User;
+
+/**
+ * Implements hook_help().
+ */
+function forum_help($route_name, RouteMatchInterface $route_match) {
+  switch ($route_name) {
+    case 'help.page.forum':
+      $output = '';
+      $output .= '<h3>' . t('About') . '</h3>';
+      $output .= '<p>' . t('The Forum module lets you create threaded discussion forums with functionality similar to other message board systems. In a forum, users post topics and threads in nested hierarchies, allowing discussions to be categorized and grouped.') . '</p>';
+      $output .= '<p>' . t('The Forum module adds and uses a content type called <em>Forum topic</em>. For background information on content types, see the <a href=":node_help">Node module help page</a>.', array(':node_help' => \Drupal::url('help.page', array('name' => 'node')))) . '</p>';
+      $output .= '<p>' . t('A forum is represented by a hierarchical structure, consisting of:');
+      $output .= '<ul>';
+      $output .= '<li>' . t('<em>Forums</em> (for example, <em>Recipes for cooking vegetables</em>)') . '</li>';
+      $output .= '<li>' . t('<em>Forum topics</em> submitted by users (for example, <em>How to cook potatoes</em>), which start discussions.') . '</li>';
+      $output .= '<li>' . t('Threaded <em>comments</em> submitted by users (for example, <em>You wash the potatoes first and then...</em>).') . '</li>';
+      $output .= '<li>' . t('Optional <em>containers</em>, used to group similar forums. Forums can be placed inside containers, and vice versa.') . '</li>';
+      $output .= '</ul>';
+      $output .= '</p>';
+      $output .= '<p>' . t('For more information, see the <a href=":forum">online documentation for the Forum module</a>.', array(':forum' => 'https://www.drupal.org/documentation/modules/forum')) . '</p>';
+      $output .= '<h3>' . t('Uses') . '</h3>';
+      $output .= '<dl>';
+      $output .= '<dt>' . t('Setting up the forum structure') . '</dt>';
+      $output .= '<dd>' . t('Visit the <a href=":forums">Forums page</a> to set up containers and forums to hold your discussion topics.', array(':forums' => \Drupal::url('forum.overview'))) . '</dd>';
+      $output .= '<dt>' . t('Starting a discussion') . '</dt>';
+      $output .= '<dd>' . t('The <a href=":create-topic">Forum topic</a> link on the <a href=":content-add">Add content</a> page creates the first post of a new threaded discussion, or thread.', array(':create-topic' => \Drupal::url('node.add', array('node_type' => 'forum')), ':content-add' => \Drupal::url('node.add_page'))) . '</dd>';
+      $output .= '<dt>' . t('Navigating in the forum') . '</dt>';
+      $output .= '<dd>' . t('Enabling the Forum module provides a default <em>Forums</em> menu item in the Tools menu that links to the <a href=":forums">Forums page</a>.', array(':forums' => \Drupal::url('forum.index'))) . '</dd>';
+      $output .= '<dt>' . t('Moving forum topics') . '</dt>';
+      $output .= '<dd>' . t('A forum topic (and all of its comments) may be moved between forums by selecting a different forum while editing a forum topic. When moving a forum topic between forums, the <em>Leave shadow copy</em> option creates a link in the original forum pointing to the new location.') . '</dd>';
+      $output .= '<dt>' . t('Locking and disabling comments') . '</dt>';
+      $output .= '<dd>' . t('Selecting <em>Closed</em> under <em>Comment settings</em> while editing a forum topic will lock (prevent new comments on) the thread. Selecting <em>Hidden</em> under <em>Comment settings</em> while editing a forum topic will hide all existing comments on the thread, and prevent new ones.') . '</dd>';
+      $output .= '</dl>';
+      return $output;
+
+    case 'forum.overview':
+      $output = '<p>' . t('Forums contain forum topics. Use containers to group related forums.') . '</p>';
+      $more_help_link = array(
+        '#type' => 'link',
+        '#url' => Url::fromRoute('help.page', ['name' => 'forum']),
+        '#title' => t('More help'),
+        '#attributes' => array(
+          'class' => array('icon-help'),
+        ),
+      );
+      $container = array(
+        '#theme' => 'container',
+        '#children' => $more_help_link,
+        '#attributes' => array(
+          'class' => array('more-link'),
+        ),
+      );
+      $output .= \Drupal::service('renderer')->renderPlain($container);
+      return $output;
+
+    case 'forum.add_container':
+      return '<p>' . t('Use containers to group related forums.') . '</p>';
+
+    case 'forum.add_forum':
+      return '<p>' . t('A forum holds related forum topics.') . '</p>';
+
+    case 'forum.settings':
+      return '<p>' . t('Adjust the display of your forum topics. Organize the forums on the <a href=":forum-structure">forum structure page</a>.', array(':forum-structure' => \Drupal::url('forum.overview'))) . '</p>';
+  }
+}
+
+/**
+ * Implements hook_theme().
+ */
+function forum_theme() {
+  return array(
+    'forums' => array(
+      'variables' => array('forums' => array(), 'topics' => array(), 'topics_pager' => array(), 'parents' => NULL, 'term' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL, 'header' => array()),
+    ),
+    'forum_list' => array(
+      'variables' => array('forums' => NULL, 'parents' => NULL, 'tid' => NULL),
+    ),
+    'forum_icon' => array(
+      'variables' => array('new_posts' => NULL, 'num_posts' => 0, 'comment_mode' => 0, 'sticky' => 0, 'first_new' => FALSE),
+    ),
+    'forum_submitted' => array(
+      'variables' => array('topic' => NULL),
+    ),
+  );
+}
+
+/**
+ * Implements hook_entity_type_build().
+ */
+function forum_entity_type_build(array &$entity_types) {
+  /** @var $entity_types \Drupal\Core\Entity\EntityTypeInterface[] */
+  // Register forum specific forms.
+  $entity_types['taxonomy_term']
+    ->setFormClass('forum', 'Drupal\forum\Form\ForumForm')
+    ->setFormClass('container', 'Drupal\forum\Form\ContainerForm')
+    ->setLinkTemplate('forum-edit-container-form', '/admin/structure/forum/edit/container/{taxonomy_term}')
+    ->setLinkTemplate('forum-delete-form', '/admin/structure/forum/delete/forum/{taxonomy_term}')
+    ->setLinkTemplate('forum-edit-form', '/admin/structure/forum/edit/forum/{taxonomy_term}');
+}
+
+/**
+ * Implements hook_entity_bundle_info_alter().
+ */
+function forum_entity_bundle_info_alter(&$bundles) {
+  // Take over URI construction for taxonomy terms that are forums.
+  if ($vid = \Drupal::config('forum.settings')->get('vocabulary')) {
+    if (isset($bundles['taxonomy_term'][$vid])) {
+      $bundles['taxonomy_term'][$vid]['uri_callback'] = 'forum_uri';
+    }
+  }
+}
+
+/**
+ * Entity URI callback used in forum_entity_bundle_info_alter().
+ */
+function forum_uri($forum) {
+  return Url::fromRoute('forum.page', ['taxonomy_term' => $forum->id()]);
+}
+
+/**
+ * Implements hook_entity_bundle_field_info_alter().
+ */
+function forum_entity_bundle_field_info_alter(&$fields, EntityTypeInterface $entity_type, $bundle) {
+  if ($entity_type->id() == 'node'  && !empty($fields['taxonomy_forums'])) {
+    $fields['taxonomy_forums']->addConstraint('ForumLeaf', []);
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_presave() for node entities.
+ *
+ * Assigns the forum taxonomy when adding a topic from within a forum.
+ */
+function forum_node_presave(EntityInterface $node) {
+  if (\Drupal::service('forum_manager')->checkNodeType($node)) {
+    // Make sure all fields are set properly:
+    $node->icon = !empty($node->icon) ? $node->icon : '';
+    if (!$node->taxonomy_forums->isEmpty()) {
+      $node->forum_tid = $node->taxonomy_forums->target_id;
+      // Only do a shadow copy check if this is not a new node.
+      if (!$node->isNew()) {
+        $old_tid = \Drupal::service('forum.index_storage')->getOriginalTermId($node);
+        if ($old_tid && isset($node->forum_tid) && ($node->forum_tid != $old_tid) && !empty($node->shadow)) {
+          // A shadow copy needs to be created. Retain new term and add old term.
+          $node->taxonomy_forums[count($node->taxonomy_forums)] = array('target_id' => $old_tid);
+        }
+      }
+    }
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_update() for node entities.
+ */
+function forum_node_update(EntityInterface $node) {
+  if (\Drupal::service('forum_manager')->checkNodeType($node)) {
+    // If this is not a new revision and does exist, update the forum record,
+    // otherwise insert a new one.
+    /** @var \Drupal\forum\ForumIndexStorageInterface $forum_index_storage */
+    $forum_index_storage = \Drupal::service('forum.index_storage');
+    if ($node->getRevisionId() == $node->original->getRevisionId() && $forum_index_storage->getOriginalTermId($node)) {
+      if (!empty($node->forum_tid)) {
+        $forum_index_storage->update($node);
+      }
+      // The node is removed from the forum.
+      else {
+        $forum_index_storage->delete($node);
+      }
+    }
+    else {
+      if (!empty($node->forum_tid)) {
+        $forum_index_storage->create($node);
+      }
+    }
+    // If the node has a shadow forum topic, update the record for this
+    // revision.
+    if (!empty($node->shadow)) {
+      $forum_index_storage->deleteRevision($node);
+      $forum_index_storage->create($node);
+    }
+
+    // If the node is published, update the forum index.
+    if ($node->isPublished()) {
+      $forum_index_storage->deleteIndex($node);
+      $forum_index_storage->createIndex($node);
+    }
+    // When a forum node is unpublished, remove it from the forum_index table.
+    else {
+      $forum_index_storage->deleteIndex($node);
+    }
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_insert() for node entities.
+ */
+function forum_node_insert(EntityInterface $node) {
+  if (\Drupal::service('forum_manager')->checkNodeType($node)) {
+    /** @var \Drupal\forum\ForumIndexStorageInterface $forum_index_storage */
+    $forum_index_storage = \Drupal::service('forum.index_storage');
+    if (!empty($node->forum_tid)) {
+      $forum_index_storage->create($node);
+    }
+
+    // If the node is published, update the forum index.
+    if ($node->isPublished()) {
+      $forum_index_storage->createIndex($node);
+    }
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_predelete() for node entities.
+ */
+function forum_node_predelete(EntityInterface $node) {
+  if (\Drupal::service('forum_manager')->checkNodeType($node)) {
+    /** @var \Drupal\forum\ForumIndexStorageInterface $forum_index_storage */
+    $forum_index_storage = \Drupal::service('forum.index_storage');
+    $forum_index_storage->delete($node);
+    $forum_index_storage->deleteIndex($node);
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_storage_load() for node entities.
+ */
+function forum_node_storage_load($nodes) {
+  $node_vids = array();
+  foreach ($nodes as $node) {
+    if (\Drupal::service('forum_manager')->checkNodeType($node)) {
+      $node_vids[] = $node->getRevisionId();
+    }
+  }
+  if (!empty($node_vids)) {
+    $result = \Drupal::service('forum.index_storage')->read($node_vids);
+    foreach ($result as $record) {
+      $nodes[$record->nid]->forum_tid = $record->tid;
+    }
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_update() for comment entities.
+ */
+function forum_comment_update(CommentInterface $comment) {
+  if ($comment->getCommentedEntityTypeId() == 'node') {
+    \Drupal::service('forum.index_storage')->updateIndex($comment->getCommentedEntity());
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_insert() for comment entities.
+ */
+function forum_comment_insert(CommentInterface $comment) {
+  if ($comment->getCommentedEntityTypeId() == 'node') {
+    \Drupal::service('forum.index_storage')->updateIndex($comment->getCommentedEntity());
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_delete() for comment entities.
+ */
+function forum_comment_delete(CommentInterface $comment) {
+  if ($comment->getCommentedEntityTypeId() == 'node') {
+    \Drupal::service('forum.index_storage')->updateIndex($comment->getCommentedEntity());
+  }
+}
+
+/**
+ * Implements hook_form_BASE_FORM_ID_alter() for \Drupal\taxonomy\VocabularyForm.
+ */
+function forum_form_taxonomy_vocabulary_form_alter(&$form, FormStateInterface $form_state, $form_id) {
+  $vid = \Drupal::config('forum.settings')->get('vocabulary');
+  $vocabulary = $form_state->getFormObject()->getEntity();
+  if ($vid == $vocabulary->id()) {
+    $form['help_forum_vocab'] = array(
+      '#markup' => t('This is the designated forum vocabulary. Some of the normal vocabulary options have been removed.'),
+      '#weight' => -1,
+    );
+    // Forum's vocabulary always has single hierarchy. Forums and containers
+    // have only one parent or no parent for root items. By default this value
+    // is 0.
+    $form['hierarchy']['#value'] = VocabularyInterface::HIERARCHY_SINGLE;
+    // Do not allow to delete forum's vocabulary.
+    $form['actions']['delete']['#access'] = FALSE;
+    // Do not allow to change a vid of forum's vocabulary.
+    $form['vid']['#disabled'] = TRUE;
+  }
+}
+
+/**
+ * Implements hook_form_FORM_ID_alter() for \Drupal\taxonomy\TermForm.
+ */
+function forum_form_taxonomy_term_form_alter(&$form, FormStateInterface $form_state, $form_id) {
+  $vid = \Drupal::config('forum.settings')->get('vocabulary');
+  if (isset($form['vid']['#value']) && $form['vid']['#value'] == $vid) {
+    // Hide multiple parents select from forum terms.
+    $form['relations']['parent']['#access'] = FALSE;
+  }
+}
+
+/**
+ * Implements hook_form_BASE_FORM_ID_alter() for \Drupal\node\NodeForm.
+ */
+function forum_form_node_form_alter(&$form, FormStateInterface $form_state, $form_id) {
+  $node = $form_state->getFormObject()->getEntity();
+  if (isset($node->taxonomy_forums) && !$node->isNew()) {
+    $forum_terms = $node->taxonomy_forums;
+    // If editing, give option to leave shadows.
+    $shadow = (count($forum_terms) > 1);
+    $form['shadow'] = array(
+      '#type' => 'checkbox',
+      '#title' => t('Leave shadow copy'),
+      '#default_value' => $shadow,
+      '#description' => t('If you move this topic, you can leave a link in the old forum to the new forum.'),
+    );
+    $form['forum_tid'] = array('#type' => 'value', '#value' => $node->forum_tid);
+  }
+
+  if (isset($form['taxonomy_forums'])) {
+    $widget =& $form['taxonomy_forums']['widget'];
+    // Make the vocabulary required for 'real' forum-nodes.
+    $widget['#required'] = TRUE;
+    $widget['#multiple'] = FALSE;
+    if (empty($widget['#default_value'])) {
+      // If there is no default forum already selected, try to get the forum
+      // ID from the URL (e.g., if we are on a page like node/add/forum/2, we
+      // expect "2" to be the ID of the forum that was requested).
+      $requested_forum_id = \Drupal::request()->query->get('forum_id');
+      $widget['#default_value'] = is_numeric($requested_forum_id) ? $requested_forum_id : '';
+    }
+  }
+}
+
+/**
+ * Implements hook_preprocess_HOOK() for block templates.
+ */
+function forum_preprocess_block(&$variables) {
+  if ($variables['configuration']['provider'] == 'forum') {
+    $variables['attributes']['role'] = 'navigation';
+  }
+}
+
+/**
+ * Implements hook_theme_suggestions_HOOK().
+ */
+function forum_theme_suggestions_forums(array $variables) {
+  $suggestions = array();
+  $tid = $variables['term']->id();
+
+  // Provide separate template suggestions based on what's being output. Topic
+  // ID is also accounted for. Check both variables to be safe then the inverse.
+  // Forums with topic IDs take precedence.
+  if ($variables['forums'] && !$variables['topics']) {
+    $suggestions[] = 'forums__containers';
+    $suggestions[] = 'forums__' . $tid;
+    $suggestions[] = 'forums__containers__' . $tid;
+  }
+  elseif (!$variables['forums'] && $variables['topics']) {
+    $suggestions[] = 'forums__topics';
+    $suggestions[] = 'forums__' . $tid;
+    $suggestions[] = 'forums__topics__' . $tid;
+  }
+  else {
+    $suggestions[] = 'forums__' . $tid;
+  }
+
+  return $suggestions;
+}
+
+/**
+ * Prepares variables for forums templates.
+ *
+ * Default template: forums.html.twig.
+ *
+ * @param array $variables
+ *   An array containing the following elements:
+ *   - forums: An array of all forum objects to display for the given taxonomy
+ *     term ID. If tid = 0 then all the top-level forums are displayed.
+ *   - topics: An array of all the topics in the current forum.
+ *   - parents: An array of taxonomy term objects that are ancestors of the
+ *     current term ID.
+ *   - term: Taxonomy term of the current forum.
+ *   - sortby: One of the following integers indicating the sort criteria:
+ *     - 1: Date - newest first.
+ *     - 2: Date - oldest first.
+ *     - 3: Posts with the most comments first.
+ *     - 4: Posts with the least comments first.
+ *   - forum_per_page: The maximum number of topics to display per page.
+ */
+function template_preprocess_forums(&$variables) {
+  $variables['tid'] = $variables['term']->id();
+  if ($variables['forums_defined'] = count($variables['forums']) || count($variables['parents'])) {
+    if (!empty($variables['forums'])) {
+      $variables['forums'] = array(
+        '#theme' => 'forum_list',
+        '#forums' => $variables['forums'],
+        '#parents' => $variables['parents'],
+        '#tid' => $variables['tid'],
+      );
+    }
+
+    if ($variables['term'] && empty($variables['term']->forum_container->value) && !empty($variables['topics'])) {
+      $forum_topic_list_header = $variables['header'];
+
+      $table = array(
+        '#theme' => 'table__forum_topic_list',
+        '#responsive' => FALSE,
+        '#attributes' => array('id' => 'forum-topic-' . $variables['tid']),
+        '#header' => array(),
+        '#rows' => array(),
+      );
+
+      if (!empty($forum_topic_list_header)) {
+        $table['#header'] = $forum_topic_list_header;
+      }
+
+      /** @var \Drupal\node\NodeInterface $topic */
+      foreach ($variables['topics'] as $id => $topic) {
+        $variables['topics'][$id]->icon = array(
+          '#theme' => 'forum_icon',
+          '#new_posts' => $topic->new,
+          '#num_posts' => $topic->comment_count,
+          '#comment_mode' => $topic->comment_mode,
+          '#sticky' => $topic->isSticky(),
+          '#first_new' => $topic->first_new,
+        );
+
+        // We keep the actual tid in forum table, if it's different from the
+        // current tid then it means the topic appears in two forums, one of
+        // them is a shadow copy.
+        if ($variables['tid'] != $topic->forum_tid) {
+          $variables['topics'][$id]->moved = TRUE;
+          $variables['topics'][$id]->title = $topic->getTitle();
+          $variables['topics'][$id]->message = \Drupal::l(t('This topic has been moved'), new Url('forum.page', ['taxonomy_term' => $topic->forum_tid]));
+        }
+        else {
+          $variables['topics'][$id]->moved = FALSE;
+          $variables['topics'][$id]->title_link = \Drupal::l($topic->getTitle(), $topic->urlInfo());
+          $variables['topics'][$id]->message = '';
+        }
+        $forum_submitted = array('#theme' => 'forum_submitted', '#topic' => (object) array(
+          'uid' => $topic->getOwnerId(),
+          'name' => $topic->getOwner()->getDisplayName(),
+          'created' => $topic->getCreatedTime(),
+        ));
+        $variables['topics'][$id]->submitted = drupal_render($forum_submitted);
+        $forum_submitted = array(
+          '#theme' => 'forum_submitted',
+          '#topic' => isset($topic->last_reply) ? $topic->last_reply : NULL,
+        );
+        $variables['topics'][$id]->last_reply = drupal_render($forum_submitted);
+
+        $variables['topics'][$id]->new_text = '';
+        $variables['topics'][$id]->new_url = '';
+
+        if ($topic->new_replies) {
+          $page_number = \Drupal::entityManager()->getStorage('comment')
+            ->getNewCommentPageNumber($topic->comment_count, $topic->new_replies, $topic, 'comment_forum');
+          $query = $page_number ? array('page' => $page_number) : NULL;
+          $variables['topics'][$id]->new_text = \Drupal::translation()->formatPlural($topic->new_replies, '1 new post<span class="visually-hidden"> in topic %title</span>', '@count new posts<span class="visually-hidden"> in topic %title</span>', array('%title' => $variables['topics'][$id]->label()));
+          $variables['topics'][$id]->new_url = \Drupal::url('entity.node.canonical', ['node' => $topic->id()], ['query' => $query, 'fragment' => 'new']);
+        }
+
+        // Build table rows from topics.
+        $row = array();
+        $row[] = array(
+          'data' => array(
+            $topic->icon,
+            array(
+              '#markup' => '<div class="forum__title"><div>' . $topic->title_link . '</div><div>' . $topic->submitted . '</div></div>',
+            ),
+          ),
+          'class' => array('forum__topic'),
+        );
+
+        if ($topic->moved) {
+          $row[] = array(
+            'data' => $topic->message,
+            'colspan' => '2',
+          );
+        }
+        else {
+          $new_replies = '';
+          if ($topic->new_replies) {
+            $new_replies = '<br /><a href="' . $topic->new_url . '">' . $topic->new_text . '</a>';
+          }
+
+          $row[] = array(
+            'data' => [
+              [
+                '#prefix' => $topic->comment_count,
+                '#markup' => $new_replies,
+              ],
+            ],
+            'class' => array('forum__replies'),
+          );
+          $row[] = array(
+            'data' => $topic->last_reply,
+            'class' => array('forum__last-reply'),
+          );
+        }
+        $table['#rows'][] = $row;
+      }
+
+      $variables['topics'] = $table;
+      $variables['topics_pager'] = array(
+        '#type' => 'pager',
+      );
+    }
+  }
+}
+
+/**
+ * Prepares variables for forum list templates.
+ *
+ * Default template: forum-list.html.twig.
+ *
+ * @param array $variables
+ *   An array containing the following elements:
+ *   - forums: An array of all forum objects to display for the given taxonomy
+ *     term ID. If tid = 0 then all the top-level forums are displayed.
+ *   - parents: An array of taxonomy term objects that are ancestors of the
+ *     current term ID.
+ *   - tid: Taxonomy term ID of the current forum.
+ */
+function template_preprocess_forum_list(&$variables) {
+  $user = \Drupal::currentUser();
+  $row = 0;
+  // Sanitize each forum so that the template can safely print the data.
+  foreach ($variables['forums'] as $id => $forum) {
+    $variables['forums'][$id]->description = array('#markup' => $forum->description->value);
+    $variables['forums'][$id]->link = forum_uri($forum);
+    $variables['forums'][$id]->name = $forum->label();
+    $variables['forums'][$id]->is_container = !empty($forum->forum_container->value);
+    $variables['forums'][$id]->zebra = $row % 2 == 0 ? 'odd' : 'even';
+    $row++;
+
+    $variables['forums'][$id]->new_text = '';
+    $variables['forums'][$id]->new_url = '';
+    $variables['forums'][$id]->new_topics = 0;
+    $variables['forums'][$id]->old_topics = $forum->num_topics;
+    $variables['forums'][$id]->icon_class = 'default';
+    $variables['forums'][$id]->icon_title = t('No new posts');
+    if ($user->isAuthenticated()) {
+      $variables['forums'][$id]->new_topics = \Drupal::service('forum_manager')->unreadTopics($forum->id(), $user->id());
+      if ($variables['forums'][$id]->new_topics) {
+        $variables['forums'][$id]->new_text = \Drupal::translation()->formatPlural($variables['forums'][$id]->new_topics, '1 new post<span class="visually-hidden"> in forum %title</span>', '@count new posts<span class="visually-hidden"> in forum %title</span>', array('%title' => $variables['forums'][$id]->label()));
+        $variables['forums'][$id]->new_url = \Drupal::url('forum.page', ['taxonomy_term' => $forum->id()], ['fragment' => 'new']);
+        $variables['forums'][$id]->icon_class = 'new';
+        $variables['forums'][$id]->icon_title = t('New posts');
+      }
+      $variables['forums'][$id]->old_topics = $forum->num_topics - $variables['forums'][$id]->new_topics;
+    }
+    $forum_submitted = array('#theme' => 'forum_submitted', '#topic' => $forum->last_post);
+    $variables['forums'][$id]->last_reply = drupal_render($forum_submitted);
+  }
+
+  $variables['pager'] = array(
+   '#type' => 'pager',
+  );
+
+  // Give meaning to $tid for themers. $tid actually stands for term ID.
+  $variables['forum_id'] = $variables['tid'];
+  unset($variables['tid']);
+}
+
+/**
+ * Prepares variables for forum icon templates.
+ *
+ * Default template: forum-icon.html.twig.
+ *
+ * @param array $variables
+ *   An array containing the following elements:
+ *   - new_posts: Indicates whether or not the topic contains new posts.
+ *   - num_posts: The total number of posts in all topics.
+ *   - comment_mode: An integer indicating whether comments are open, closed,
+ *     or hidden.
+ *   - sticky: Indicates whether the topic is sticky.
+ *   - first_new: Indicates whether this is the first topic with new posts.
+ */
+function template_preprocess_forum_icon(&$variables) {
+  $variables['hot_threshold'] = \Drupal::config('forum.settings')->get('topics.hot_threshold');
+
+  if ($variables['num_posts'] > $variables['hot_threshold']) {
+    $variables['icon_status'] = $variables['new_posts'] ? 'hot-new' : 'hot';
+    $variables['icon_title'] = $variables['new_posts'] ? t('Hot topic, new comments') : t('Hot topic');
+  }
+  else {
+    $variables['icon_status'] = $variables['new_posts'] ? 'new' : 'default';
+    $variables['icon_title'] = $variables['new_posts'] ? t('New comments') : t('Normal topic');
+  }
+
+  if ($variables['comment_mode'] == CommentItemInterface::CLOSED || $variables['comment_mode'] == CommentItemInterface::HIDDEN) {
+    $variables['icon_status'] = 'closed';
+    $variables['icon_title'] = t('Closed topic');
+  }
+
+  if ($variables['sticky'] == 1) {
+    $variables['icon_status'] = 'sticky';
+    $variables['icon_title'] = t('Sticky topic');
+  }
+
+  $variables['attributes']['title'] = $variables['icon_title'];
+}
+
+/**
+ * Prepares variables for forum submission information templates.
+ *
+ * The submission information will be displayed in the forum list and topic
+ * list.
+ *
+ * Default template: forum-submitted.html.twig.
+ *
+ * @param array $variables
+ *   An array containing the following elements:
+ *   - topic: The topic object.
+ */
+function template_preprocess_forum_submitted(&$variables) {
+  $variables['author'] = '';
+  if (isset($variables['topic']->uid)) {
+    $username = array('#theme' => 'username', '#account' => User::load($variables['topic']->uid));
+    $variables['author'] = drupal_render($username);
+  }
+  $variables['time'] = isset($variables['topic']->created) ? \Drupal::service('date.formatter')->formatTimeDiffSince($variables['topic']->created) : '';
+}

web/core/modules/forum/forum.permissions.yml

@@ -0,0 +1,2 @@
+administer forums:
+  title: 'Administer forums'

web/core/modules/forum/forum.routing.yml

@@ -0,0 +1,71 @@
+entity.taxonomy_term.forum_delete_form:
+  path: '/admin/structure/forum/delete/forum/{taxonomy_term}'
+  defaults:
+    _form: '\Drupal\forum\Form\DeleteForm'
+    _title: 'Delete forum'
+  requirements:
+    _permission: 'administer forums'
+
+forum.settings:
+  path: '/admin/structure/forum/settings'
+  defaults:
+    _form: '\Drupal\forum\ForumSettingsForm'
+    _title: 'Forums'
+  requirements:
+    _permission: 'administer forums'
+
+forum.index:
+  path: '/forum'
+  defaults:
+    _controller: '\Drupal\forum\Controller\ForumController::forumIndex'
+    _title: 'Forums'
+  requirements:
+    _permission: 'access content'
+
+forum.page:
+  path: '/forum/{taxonomy_term}'
+  defaults:
+    _controller: '\Drupal\forum\Controller\ForumController::forumPage'
+    _title_callback: '\Drupal\taxonomy\Controller\TaxonomyController::termTitle'
+  requirements:
+    _permission: 'access content'
+
+forum.add_container:
+  path: '/admin/structure/forum/add/container'
+  defaults:
+    _controller: '\Drupal\forum\Controller\ForumController::addContainer'
+    _title: 'Add container'
+  requirements:
+    _permission: 'administer forums'
+
+forum.add_forum:
+  path: '/admin/structure/forum/add/forum'
+  defaults:
+    _controller: '\Drupal\forum\Controller\ForumController::addForum'
+    _title: 'Add forum'
+  requirements:
+    _permission: 'administer forums'
+
+entity.taxonomy_term.forum_edit_container_form:
+  path: '/admin/structure/forum/edit/container/{taxonomy_term}'
+  defaults:
+    _entity_form: 'taxonomy_term.container'
+    _title: 'Edit container'
+  requirements:
+    _permission: 'administer forums'
+
+entity.taxonomy_term.forum_edit_form:
+  path: '/admin/structure/forum/edit/forum/{taxonomy_term}'
+  defaults:
+    _entity_form: 'taxonomy_term.forum'
+    _title: 'Edit forum'
+  requirements:
+    _permission: 'administer forums'
+
+forum.overview:
+  path: '/admin/structure/forum'
+  defaults:
+    _form: '\Drupal\forum\Form\Overview'
+    _title: 'Forums'
+  requirements:
+    _permission: 'administer forums'

web/core/modules/forum/forum.services.yml

@@ -0,0 +1,28 @@
+services:
+  forum_manager:
+    class: Drupal\forum\ForumManager
+    arguments: ['@config.factory', '@entity.manager', '@database', '@string_translation', '@comment.manager']
+    tags:
+      - { name: backend_overridable }
+  forum.breadcrumb.node:
+    class: Drupal\forum\Breadcrumb\ForumNodeBreadcrumbBuilder
+    arguments: ['@entity.manager', '@config.factory', '@forum_manager', '@string_translation']
+    tags:
+      - { name: breadcrumb_builder, priority: 1001 }
+  forum.breadcrumb.listing:
+    class: Drupal\forum\Breadcrumb\ForumListingBreadcrumbBuilder
+    arguments: ['@entity.manager', '@config.factory', '@forum_manager', '@string_translation']
+    tags:
+      - { name: breadcrumb_builder, priority: 1001 }
+  forum.index_storage:
+    class: Drupal\forum\ForumIndexStorage
+    arguments: ['@database', '@forum_manager']
+    tags:
+      - { name: backend_overridable }
+
+  forum.uninstall_validator:
+    class: Drupal\forum\ForumUninstallValidator
+    tags:
+      - { name: module_install.uninstall_validator }
+    arguments: ['@entity.manager', '@entity.query', '@config.factory', '@string_translation']
+    lazy: true

web/core/modules/forum/forum.views.inc

@@ -0,0 +1,157 @@
+<?php
+
+/**
+ * @file
+ * Provide views data for forum.module.
+ */
+
+/**
+ * Implements hook_views_data().
+ */
+function forum_views_data() {
+
+  $data['forum_index']['table']['group'] = t('Forum');
+  $data['forum_index']['table']['base'] = array(
+    'field' => 'nid',
+    'title' => t('Forum content'),
+    'access query tag' => 'node_access',
+  );
+
+  $data['forum_index']['nid'] = array(
+    'title' => t('Nid'),
+    'help' => t('The content ID of the forum index entry.'),
+    'field' => array(
+      'id' => 'numeric',
+    ),
+    'filter' => array(
+      'id' => 'numeric',
+    ),
+    'argument' => array(
+      'id' => 'numeric',
+    ),
+    'sort' => array(
+      'id' => 'standard',
+    ),
+    'relationship' => array(
+      'base' => 'node',
+      'base field' => 'nid',
+      'label' => t('Node'),
+    ),
+  );
+
+  $data['forum_index']['title'] = array(
+    'title' => t('Title'),
+    'help' => t('The content title.'),
+    'field' => array(
+      'id' => 'standard',
+      'link_to_node default' => TRUE,
+    ),
+    'sort' => array(
+      'id' => 'standard',
+    ),
+    'filter' => array(
+      'id' => 'string',
+    ),
+    'argument' => array(
+      'id' => 'string',
+    ),
+  );
+
+  $data['forum_index']['tid'] = array(
+    'title' => t('Has taxonomy term ID'),
+    'help' => t('Display content if it has the selected taxonomy terms.'),
+    'argument' => array(
+      'id' => 'taxonomy_index_tid',
+      'name table' => 'taxonomy_term_data',
+      'name field' => 'name',
+      'empty field name' => t('Uncategorized'),
+      'numeric' => TRUE,
+      'skip base' => 'taxonomy_term_data',
+    ),
+    'field' => array(
+      'id' => 'numeric',
+    ),
+    'filter' => array(
+      'title' => t('Has taxonomy term'),
+      'id' => 'taxonomy_index_tid',
+      'hierarchy table' => 'taxonomy_term_hierarchy',
+      'numeric' => TRUE,
+      'skip base' => 'taxonomy_term_data',
+      'allow empty' => TRUE,
+    ),
+    'relationship' => array(
+      'base' => 'taxonomy_term',
+      'base field' => 'tid',
+      'label' => t('Term'),
+    ),
+  );
+
+
+  $data['forum_index']['created'] = array(
+    'title' => t('Post date'),
+    'help' => t('The date the content was posted.'),
+    'field' => array(
+      'id' => 'date',
+    ),
+    'sort' => array(
+      'id' => 'date'
+    ),
+    'filter' => array(
+      'id' => 'date',
+    ),
+  );
+
+  $data['forum_index']['sticky'] = array(
+    'title' => t('Sticky'),
+    'help' => t('Whether or not the content is sticky.'),
+    'field' => array(
+      'id' => 'boolean',
+      'click sortable' => TRUE,
+      'output formats' => array(
+        'sticky' => array(t('Sticky'), t('Not sticky')),
+      ),
+    ),
+    'filter' => array(
+      'id' => 'boolean',
+      'label' => t('Sticky'),
+      'type' => 'yes-no',
+    ),
+    'sort' => array(
+      'id' => 'standard',
+      'help' => t('Whether or not the content is sticky. To list sticky content first, set this to descending.'),
+    ),
+  );
+
+  $data['forum_index']['last_comment_timestamp'] = array(
+    'title' => t('Last comment time'),
+    'help' => t('Date and time of when the last comment was posted.'),
+    'field' => array(
+      'id' => 'comment_last_timestamp',
+    ),
+    'sort' => array(
+      'id' => 'date',
+    ),
+    'filter' => array(
+      'id' => 'date',
+    ),
+  );
+
+  $data['forum_index']['comment_count'] = array(
+    'title' => t('Comment count'),
+    'help' => t('The number of comments a node has.'),
+    'field' => array(
+      'id' => 'numeric',
+    ),
+    'filter' => array(
+      'id' => 'numeric',
+    ),
+    'sort' => array(
+      'id' => 'standard',
+    ),
+    'argument' => array(
+      'id' => 'standard',
+    ),
+  );
+
+  return $data;
+}

web/core/modules/forum/migration_templates/d6_forum_settings.yml

@@ -0,0 +1,29 @@
+id: d6_forum_settings
+label: Forum configuration
+migration_tags:
+  - Drupal 6
+source:
+  plugin: variable
+  variables:
+    - forum_hot_topic
+    - forum_per_page
+    - forum_order
+    - forum_block_num_0
+    - forum_block_num_1
+    - forum_nav_vocabulary
+process:
+  'block/active/limit': forum_block_num_0
+  'block/new/limit': forum_block_num_1
+  'topics/hot_threshold': forum_hot_topic
+  'topics/page_limit': forum_per_page
+  'topics/order': forum_order
+  vocabulary:
+    plugin: migration
+    migration: d6_taxonomy_vocabulary
+    source: forum_nav_vocabulary
+destination:
+  plugin: config
+  config_name: forum.settings
+migration_dependencies:
+  required:
+    - d6_taxonomy_vocabulary

web/core/modules/forum/migration_templates/d7_forum_settings.yml

@@ -0,0 +1,29 @@
+id: d7_forum_settings
+label: Forum configuration
+migration_tags:
+  - Drupal 7
+source:
+  plugin: variable
+  variables:
+    - forum_hot_topic
+    - forum_per_page
+    - forum_order
+    - forum_block_num_active
+    - forum_block_num_new
+    - forum_nav_vocabulary
+process:
+  'block/active/limit': forum_block_num_active
+  'block/new/limit': forum_block_num_new
+  'topics/hot_threshold': forum_hot_topic
+  'topics/page_limit': forum_per_page
+  'topics/order': forum_order
+  vocabulary:
+    plugin: migration
+    migration: d7_taxonomy_vocabulary
+    source: forum_nav_vocabulary
+destination:
+  plugin: config
+  config_name: forum.settings
+migration_dependencies:
+  required:
+    - d7_taxonomy_vocabulary

web/core/modules/forum/src/Breadcrumb/ForumBreadcrumbBuilderBase.php

@@ -0,0 +1,82 @@
+<?php
+
+namespace Drupal\forum\Breadcrumb;
+
+use Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface;
+use Drupal\Core\Breadcrumb\Breadcrumb;
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Link;
+use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\forum\ForumManagerInterface;
+
+/**
+ * Provides a forum breadcrumb base class.
+ *
+ * This just holds the dependency-injected config, entity manager, and forum
+ * manager objects.
+ */
+abstract class ForumBreadcrumbBuilderBase implements BreadcrumbBuilderInterface {
+  use StringTranslationTrait;
+
+  /**
+   * Configuration object for this builder.
+   *
+   * @var \Drupal\Core\Config\Config
+   */
+  protected $config;
+
+  /**
+   * The entity manager.
+   *
+   * @var \Drupal\Core\Entity\EntityManagerInterface
+   */
+  protected $entityManager;
+
+  /**
+   * The forum manager service.
+   *
+   * @var \Drupal\forum\ForumManagerInterface
+   */
+  protected $forumManager;
+
+  /**
+   * Constructs a forum breadcrumb builder object.
+   *
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   *   The entity manager.
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The configuration factory.
+   * @param \Drupal\forum\ForumManagerInterface $forum_manager
+   *   The forum manager service.
+   * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
+   *   The string translation service.
+   */
+  public function __construct(EntityManagerInterface $entity_manager, ConfigFactoryInterface $config_factory, ForumManagerInterface $forum_manager, TranslationInterface $string_translation) {
+    $this->entityManager = $entity_manager;
+    $this->config = $config_factory->get('forum.settings');
+    $this->forumManager = $forum_manager;
+    $this->setStringTranslation($string_translation);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build(RouteMatchInterface $route_match) {
+    $breadcrumb = new Breadcrumb();
+    $breadcrumb->addCacheContexts(['route']);
+
+    $links[] = Link::createFromRoute($this->t('Home'), '<front>');
+
+    $vocabulary = $this->entityManager
+      ->getStorage('taxonomy_vocabulary')
+      ->load($this->config->get('vocabulary'));
+    $breadcrumb->addCacheableDependency($vocabulary);
+    $links[] = Link::createFromRoute($vocabulary->label(), 'forum.index');
+
+    return $breadcrumb->setLinks($links);
+  }
+
+}

web/core/modules/forum/src/Breadcrumb/ForumListingBreadcrumbBuilder.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace Drupal\forum\Breadcrumb;
+
+use Drupal\Core\Link;
+use Drupal\Core\Routing\RouteMatchInterface;
+
+/**
+ * Provides a breadcrumb builder base class for forum listing pages.
+ */
+class ForumListingBreadcrumbBuilder extends ForumBreadcrumbBuilderBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function applies(RouteMatchInterface $route_match) {
+    return $route_match->getRouteName() == 'forum.page' && $route_match->getParameter('taxonomy_term');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build(RouteMatchInterface $route_match) {
+    $breadcrumb = parent::build($route_match);
+    $breadcrumb->addCacheContexts(['route']);
+
+    // Add all parent forums to breadcrumbs.
+    /** @var \Drupal\Taxonomy\TermInterface $term */
+    $term = $route_match->getParameter('taxonomy_term');
+    $term_id = $term->id();
+    $breadcrumb->addCacheableDependency($term);
+
+    $parents = $this->forumManager->getParents($term_id);
+    if ($parents) {
+      foreach (array_reverse($parents) as $parent) {
+        if ($parent->id() != $term_id) {
+          $breadcrumb->addCacheableDependency($parent);
+          $breadcrumb->addLink(Link::createFromRoute($parent->label(), 'forum.page', [
+            'taxonomy_term' => $parent->id(),
+          ]));
+        }
+      }
+    }
+
+    return $breadcrumb;
+  }
+
+}

web/core/modules/forum/src/Breadcrumb/ForumNodeBreadcrumbBuilder.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace Drupal\forum\Breadcrumb;
+
+use Drupal\Core\Link;
+use Drupal\Core\Routing\RouteMatchInterface;
+
+/**
+ * Breadcrumb builder for forum nodes.
+ */
+class ForumNodeBreadcrumbBuilder extends ForumBreadcrumbBuilderBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function applies(RouteMatchInterface $route_match) {
+    return $route_match->getRouteName() == 'entity.node.canonical'
+      && $route_match->getParameter('node')
+      && $this->forumManager->checkNodeType($route_match->getParameter('node'));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build(RouteMatchInterface $route_match) {
+    $breadcrumb = parent::build($route_match);
+    $breadcrumb->addCacheContexts(['route']);
+
+    $parents = $this->forumManager->getParents($route_match->getParameter('node')->forum_tid);
+    if ($parents) {
+      $parents = array_reverse($parents);
+      foreach ($parents as $parent) {
+        $breadcrumb->addCacheableDependency($parent);
+        $breadcrumb->addLink(Link::createFromRoute($parent->label(), 'forum.page',
+          array(
+            'taxonomy_term' => $parent->id(),
+          )
+        ));
+      }
+    }
+
+    return $breadcrumb;
+  }
+
+}

web/core/modules/forum/src/Controller/ForumController.php

@@ -0,0 +1,338 @@
+<?php
+
+namespace Drupal\forum\Controller;
+
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Controller\ControllerBase;
+use Drupal\Core\Entity\EntityAccessControlHandlerInterface;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Render\RendererInterface;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\Url;
+use Drupal\forum\ForumManagerInterface;
+use Drupal\taxonomy\TermInterface;
+use Drupal\taxonomy\TermStorageInterface;
+use Drupal\taxonomy\VocabularyStorageInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Controller routines for forum routes.
+ */
+class ForumController extends ControllerBase {
+
+  /**
+   * Forum manager service.
+   *
+   * @var \Drupal\forum\ForumManagerInterface
+   */
+  protected $forumManager;
+
+  /**
+   * Vocabulary storage.
+   *
+   * @var \Drupal\taxonomy\VocabularyStorageInterface
+   */
+  protected $vocabularyStorage;
+
+  /**
+   * Term storage.
+   *
+   * @var \Drupal\taxonomy\TermStorageInterface
+   */
+  protected $termStorage;
+
+  /**
+   * Node access control handler.
+   *
+   * @var \Drupal\Core\Entity\EntityAccessControlHandlerInterface
+   */
+  protected $nodeAccess;
+
+  /**
+   * Field map of existing fields on the site.
+   *
+   * @var array
+   */
+  protected $fieldMap;
+
+  /**
+   * Node type storage handler.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  protected $nodeTypeStorage;
+
+  /**
+   * The renderer.
+   *
+   * @var \Drupal\Core\Render\RendererInterface
+   */
+  protected $renderer;
+
+  /**
+   * Node entity type, we need to get cache tags from here.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeInterface
+   */
+  protected $nodeEntityTypeDefinition;
+
+  /**
+   * Comment entity type, we need to get cache tags from here.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeInterface
+   */
+  protected $commentEntityTypeDefinition;
+
+  /**
+   * Constructs a ForumController object.
+   *
+   * @param \Drupal\forum\ForumManagerInterface $forum_manager
+   *   The forum manager service.
+   * @param \Drupal\taxonomy\VocabularyStorageInterface $vocabulary_storage
+   *   Vocabulary storage.
+   * @param \Drupal\taxonomy\TermStorageInterface $term_storage
+   *   Term storage.
+   * @param \Drupal\Core\Session\AccountInterface $current_user
+   *   The current logged in user.
+   * @param \Drupal\Core\Entity\EntityAccessControlHandlerInterface $node_access
+   *   Node access control handler.
+   * @param array $field_map
+   *   Array of active fields on the site.
+   * @param \Drupal\Core\Entity\EntityStorageInterface $node_type_storage
+   *   Node type storage handler.
+   * @param \Drupal\Core\Render\RendererInterface $renderer
+   *   The renderer.
+   * @param \Drupal\Core\Entity\EntityTypeInterface $node_entity_type_definition
+   *   Node entity type definition object
+   * @param \Drupal\Core\Entity\EntityTypeInterface $comment_entity_type_definition
+   *   Comment entity type definition object
+   */
+  public function __construct(ForumManagerInterface $forum_manager, VocabularyStorageInterface $vocabulary_storage, TermStorageInterface $term_storage, AccountInterface $current_user, EntityAccessControlHandlerInterface $node_access, array $field_map, EntityStorageInterface $node_type_storage, RendererInterface $renderer, EntityTypeInterface $node_entity_type_definition, EntityTypeInterface $comment_entity_type_definition) {
+    $this->forumManager = $forum_manager;
+    $this->vocabularyStorage = $vocabulary_storage;
+    $this->termStorage = $term_storage;
+    $this->currentUser = $current_user;
+    $this->nodeAccess = $node_access;
+    $this->fieldMap = $field_map;
+    $this->nodeTypeStorage = $node_type_storage;
+    $this->renderer = $renderer;
+    $this->nodeEntityTypeDefinition = $node_entity_type_definition;
+    $this->commentEntityTypeDefinition = $comment_entity_type_definition;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    /** @var \Drupal\Core\Entity\EntityManagerInterface $entity_manager */
+    $entity_manager = $container->get('entity.manager');
+
+    return new static(
+      $container->get('forum_manager'),
+      $entity_manager->getStorage('taxonomy_vocabulary'),
+      $entity_manager->getStorage('taxonomy_term'),
+      $container->get('current_user'),
+      $entity_manager->getAccessControlHandler('node'),
+      $entity_manager->getFieldMap(),
+      $entity_manager->getStorage('node_type'),
+      $container->get('renderer'),
+      $entity_manager->getDefinition('node'),
+      $entity_manager->getDefinition('comment')
+    );
+  }
+
+  /**
+   * Returns forum page for a given forum.
+   *
+   * @param \Drupal\taxonomy\TermInterface $taxonomy_term
+   *   The forum to render the page for.
+   *
+   * @return array
+   *   A render array.
+   */
+  public function forumPage(TermInterface $taxonomy_term) {
+    // Get forum details.
+    $taxonomy_term->forums = $this->forumManager->getChildren($this->config('forum.settings')->get('vocabulary'), $taxonomy_term->id());
+    $taxonomy_term->parents = $this->forumManager->getParents($taxonomy_term->id());
+
+    if (empty($taxonomy_term->forum_container->value)) {
+      $build = $this->forumManager->getTopics($taxonomy_term->id(), $this->currentUser());
+      $topics = $build['topics'];
+      $header = $build['header'];
+    }
+    else {
+      $topics = [];
+      $header = [];
+    }
+    return $this->build($taxonomy_term->forums, $taxonomy_term, $topics, $taxonomy_term->parents, $header);
+  }
+
+  /**
+   * Returns forum index page.
+   *
+   * @return array
+   *   A render array.
+   */
+  public function forumIndex() {
+    $vocabulary = $this->vocabularyStorage->load($this->config('forum.settings')->get('vocabulary'));
+    $index = $this->forumManager->getIndex();
+    $build = $this->build($index->forums, $index);
+    if (empty($index->forums)) {
+      // Root of empty forum.
+      $build['#title'] = $this->t('No forums defined');
+    }
+    else {
+      // Set the page title to forum's vocabulary name.
+      $build['#title'] = $vocabulary->label();
+      $this->renderer->addCacheableDependency($build, $vocabulary);
+    }
+    return $build;
+  }
+
+  /**
+   * Returns a renderable forum index page array.
+   *
+   * @param array $forums
+   *   A list of forums.
+   * @param \Drupal\taxonomy\TermInterface $term
+   *   The taxonomy term of the forum.
+   * @param array $topics
+   *   The topics of this forum.
+   * @param array $parents
+   *   The parent forums in relation this forum.
+   * @param array $header
+   *   Array of header cells.
+   *
+   * @return array
+   *   A render array.
+   */
+  protected function build($forums, TermInterface $term, $topics = array(), $parents = array(), $header = array()) {
+    $config = $this->config('forum.settings');
+    $build = array(
+      '#theme' => 'forums',
+      '#forums' => $forums,
+      '#topics' => $topics,
+      '#parents' => $parents,
+      '#header' => $header,
+      '#term' => $term,
+      '#sortby' => $config->get('topics.order'),
+      '#forums_per_page' => $config->get('topics.page_limit'),
+    );
+    if (empty($term->forum_container->value)) {
+      $build['#attached']['feed'][] = array('taxonomy/term/' . $term->id() . '/feed', 'RSS - ' . $term->getName());
+    }
+    $this->renderer->addCacheableDependency($build, $config);
+
+    foreach ($forums as $forum) {
+      $this->renderer->addCacheableDependency($build, $forum);
+    }
+    foreach ($topics as $topic) {
+      $this->renderer->addCacheableDependency($build, $topic);
+    }
+    foreach ($parents as $parent) {
+      $this->renderer->addCacheableDependency($build, $parent);
+    }
+    $this->renderer->addCacheableDependency($build, $term);
+
+    return [
+      'action' => $this->buildActionLinks($config->get('vocabulary'), $term),
+      'forum' => $build,
+      '#cache' => [
+        'tags' => Cache::mergeTags($this->nodeEntityTypeDefinition->getListCacheTags(), $this->commentEntityTypeDefinition->getListCacheTags()),
+      ],
+    ];
+  }
+
+  /**
+   * Returns add forum entity form.
+   *
+   * @return array
+   *   Render array for the add form.
+   */
+  public function addForum() {
+    $vid = $this->config('forum.settings')->get('vocabulary');
+    $taxonomy_term = $this->termStorage->create(array(
+      'vid' => $vid,
+      'forum_controller' => 0,
+    ));
+    return $this->entityFormBuilder()->getForm($taxonomy_term, 'forum');
+  }
+
+  /**
+   * Returns add container entity form.
+   *
+   * @return array
+   *   Render array for the add form.
+   */
+  public function addContainer() {
+    $vid = $this->config('forum.settings')->get('vocabulary');
+    $taxonomy_term = $this->termStorage->create(array(
+      'vid' => $vid,
+      'forum_container' => 1,
+    ));
+    return $this->entityFormBuilder()->getForm($taxonomy_term, 'container');
+  }
+
+  /**
+   * Generates an action link to display at the top of the forum listing.
+   *
+   * @param string $vid
+   *   Vocabulary ID.
+   * @param \Drupal\taxonomy\TermInterface $forum_term
+   *   The term for which the links are to be built.
+   *
+   * @return array
+   *   Render array containing the links.
+   */
+  protected function buildActionLinks($vid, TermInterface $forum_term = NULL) {
+    $user = $this->currentUser();
+
+    $links = [];
+    // Loop through all bundles for forum taxonomy vocabulary field.
+    foreach ($this->fieldMap['node']['taxonomy_forums']['bundles'] as $type) {
+      if ($this->nodeAccess->createAccess($type)) {
+        $node_type = $this->nodeTypeStorage->load($type);
+        $links[$type] = [
+          '#attributes' => ['class' => ['action-links']],
+          '#theme' => 'menu_local_action',
+          '#link' => [
+            'title' => $this->t('Add new @node_type', [
+              '@node_type' => $this->nodeTypeStorage->load($type)->label(),
+            ]),
+            'url' => Url::fromRoute('node.add', ['node_type' => $type]),
+          ],
+          '#cache' => [
+            'tags' => $node_type->getCacheTags(),
+          ],
+        ];
+        if ($forum_term && $forum_term->bundle() == $vid) {
+          // We are viewing a forum term (specific forum), append the tid to
+          // the url.
+          $links[$type]['#link']['localized_options']['query']['forum_id'] = $forum_term->id();
+        }
+      }
+    }
+    if (empty($links)) {
+      // Authenticated user does not have access to create new topics.
+      if ($user->isAuthenticated()) {
+        $links['disallowed'] = [
+          '#markup' => $this->t('You are not allowed to post new content in the forum.'),
+        ];
+      }
+      // Anonymous user does not have access to create new topics.
+      else {
+        $links['login'] = [
+          '#attributes' => ['class' => ['action-links']],
+          '#theme' => 'menu_local_action',
+          '#link' => array(
+            'title' => $this->t('Log in to post new content in the forum.'),
+            'url' => Url::fromRoute('user.login', [], ['query' => $this->getDestinationArray()]),
+          ),
+        ];
+      }
+    }
+    return $links;
+  }
+
+}

web/core/modules/forum/src/Form/ContainerForm.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Drupal\forum\Form;
+
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Base form for container term edit forms.
+ */
+class ContainerForm extends ForumForm {
+
+  /**
+   * Reusable url stub to use in watchdog messages.
+   *
+   * @var string
+   */
+  protected $urlStub = 'container';
+
+  /**
+   * {@inheritdoc}
+   */
+  public function form(array $form, FormStateInterface $form_state) {
+    $taxonomy_term = $this->entity;
+    // Build the bulk of the form from the parent forum form.
+    $form = parent::form($form, $form_state, $taxonomy_term);
+
+    // Set the title and description of the name field.
+    $form['name']['#title'] = $this->t('Container name');
+    $form['name']['#description'] = $this->t('Short but meaningful name for this collection of related forums.');
+
+    // Alternate description for the container parent.
+    $form['parent'][0]['#description'] = $this->t('Containers are usually placed at the top (root) level, but may also be placed inside another container or forum.');
+    $this->forumFormType = $this->t('forum container');
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildEntity(array $form, FormStateInterface $form_state) {
+    $entity = parent::buildEntity($form, $form_state);
+    $entity->forum_container = TRUE;
+    return $entity;
+  }
+
+}

web/core/modules/forum/src/Form/DeleteForm.php

@@ -0,0 +1,69 @@
+<?php
+
+namespace Drupal\forum\Form;
+
+use Drupal\Core\Form\ConfirmFormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Url;
+use Drupal\taxonomy\TermInterface;
+
+/**
+ * Builds the form to delete a forum term.
+ */
+class DeleteForm extends ConfirmFormBase {
+
+  /**
+   * The taxonomy term being deleted.
+   *
+   * @var \Drupal\taxonomy\TermInterface
+   */
+  protected $taxonomyTerm;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'forum_confirm_delete';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getQuestion() {
+    return $this->t('Are you sure you want to delete the forum %label?', array('%label' => $this->taxonomyTerm->label()));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCancelUrl() {
+    return new Url('forum.overview');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getConfirmText() {
+    return $this->t('Delete');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state, TermInterface $taxonomy_term = NULL) {
+    $this->taxonomyTerm = $taxonomy_term;
+
+    return parent::buildForm($form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $this->taxonomyTerm->delete();
+    drupal_set_message($this->t('The forum %label and all sub-forums have been deleted.', array('%label' => $this->taxonomyTerm->label())));
+    $this->logger('forum')->notice('forum: deleted %label and all its sub-forums.', array('%label' => $this->taxonomyTerm->label()));
+    $form_state->setRedirectUrl($this->getCancelUrl());
+  }
+
+}

web/core/modules/forum/src/Form/ForumForm.php

@@ -0,0 +1,168 @@
+<?php
+
+namespace Drupal\forum\Form;
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Url;
+use Drupal\taxonomy\TermForm;
+
+/**
+ * Base form for forum term edit forms.
+ */
+class ForumForm extends TermForm {
+
+  /**
+   * Reusable type field to use in status messages.
+   *
+   * @var string
+   */
+  protected $forumFormType;
+
+  /**
+   * Reusable url stub to use in watchdog messages.
+   *
+   * @var string
+   */
+  protected $urlStub = 'forum';
+
+  /**
+   * {@inheritdoc}
+   */
+  public function form(array $form, FormStateInterface $form_state) {
+    $taxonomy_term = $this->entity;
+    // Build the bulk of the form from the parent taxonomy term form.
+    $form = parent::form($form, $form_state, $taxonomy_term);
+
+    // Set the title and description of the name field.
+    $form['name']['#title'] = $this->t('Forum name');
+    $form['name']['#description'] = $this->t('Short but meaningful name for this collection of threaded discussions.');
+
+    // Change the description.
+    $form['description']['#description'] = $this->t('Description and guidelines for discussions within this forum.');
+
+    // Re-use the weight field.
+    $form['weight'] = $form['relations']['weight'];
+
+    // Remove the remaining relations fields.
+    unset($form['relations']);
+
+    // Our parent field is different to the taxonomy term.
+    $form['parent']['#tree'] = TRUE;
+    $form['parent'][0] = $this->forumParentSelect($taxonomy_term->id(), $this->t('Parent'));
+
+    $form['#theme_wrappers'] = array('form__forum');
+    $this->forumFormType = $this->t('forum');
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildEntity(array $form, FormStateInterface $form_state) {
+    $term = parent::buildEntity($form, $form_state);
+
+    // Assign parents from forum parent select field.
+    $term->parent = array($form_state->getValue(array('parent', 0)));
+
+    return $term;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function save(array $form, FormStateInterface $form_state) {
+    $term = $this->entity;
+    $term_storage = $this->entityManager->getStorage('taxonomy_term');
+    $status = $term_storage->save($term);
+
+    $route_name = $this->urlStub == 'container' ? 'entity.taxonomy_term.forum_edit_container_form' : 'entity.taxonomy_term.forum_edit_form';
+    $route_parameters  = ['taxonomy_term' => $term->id()];
+    $link = $this->l($this->t('Edit'), new Url($route_name, $route_parameters));
+    $view_link = $term->link($term->getName());
+    switch ($status) {
+      case SAVED_NEW:
+        drupal_set_message($this->t('Created new @type %term.', array('%term' => $view_link, '@type' => $this->forumFormType)));
+        $this->logger('forum')->notice('Created new @type %term.', array('%term' => $term->getName(), '@type' => $this->forumFormType, 'link' => $link));
+        $form_state->setValue('tid', $term->id());
+        break;
+
+      case SAVED_UPDATED:
+        drupal_set_message($this->t('The @type %term has been updated.', array('%term' => $term->getName(), '@type' => $this->forumFormType)));
+        $this->logger('forum')->notice('Updated @type %term.', array('%term' => $term->getName(), '@type' => $this->forumFormType, 'link' => $link));
+        break;
+    }
+
+    $form_state->setRedirect('forum.overview');
+    return $term;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function actions(array $form, FormStateInterface $form_state) {
+    $actions = parent::actions($form, $form_state);
+
+    if (!$this->entity->isNew() && $this->entity->hasLinkTemplate('forum-delete-form')) {
+      $actions['delete']['#url'] = $this->entity->urlInfo('forum-delete-form');
+    }
+    else {
+      unset($actions['delete']);
+    }
+
+    return $actions;
+  }
+
+  /**
+   * Returns a select box for available parent terms.
+   *
+   * @param int $tid
+   *   ID of the term that is being added or edited.
+   * @param string $title
+   *   Title for the select box.
+   *
+   * @return array
+   *   A select form element.
+   */
+  protected function forumParentSelect($tid, $title) {
+    $taxonomy_storage = $this->entityManager->getStorage('taxonomy_term');
+    $parents = $taxonomy_storage->loadParents($tid);
+    if ($parents) {
+      $parent = array_shift($parents);
+      $parent = $parent->id();
+    }
+    else {
+      $parent = 0;
+    }
+
+    $vid = $this->config('forum.settings')->get('vocabulary');
+    $children = $taxonomy_storage->loadTree($vid, $tid, NULL, TRUE);
+
+    // A term can't be the child of itself, nor of its children.
+    foreach ($children as $child) {
+      $exclude[] = $child->tid;
+    }
+    $exclude[] = $tid;
+
+    $tree = $taxonomy_storage->loadTree($vid, 0, NULL, TRUE);
+    $options[0] = '<' . $this->t('root') . '>';
+    if ($tree) {
+      foreach ($tree as $term) {
+        if (!in_array($term->id(), $exclude)) {
+          $options[$term->id()] = str_repeat(' -- ', $term->depth) . $term->getName();
+        }
+      }
+    }
+
+    $description = $this->t('Forums may be placed at the top (root) level, or inside another container or forum.');
+
+    return array(
+      '#type' => 'select',
+      '#title' => $title,
+      '#default_value' => $parent,
+      '#options' => $options,
+      '#description' => $description,
+      '#required' => TRUE,
+    );
+  }
+
+}

web/core/modules/forum/src/Form/Overview.php

@@ -0,0 +1,90 @@
+<?php
+
+namespace Drupal\forum\Form;
+
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Render\Element;
+use Drupal\Core\Url;
+use Drupal\taxonomy\Form\OverviewTerms;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+
+/**
+ * Provides forum overview form for the forum vocabulary.
+ */
+class Overview extends OverviewTerms {
+
+  /**
+   * Entity manager Service Object.
+   *
+   * @var \Drupal\Core\Entity\EntityManagerInterface
+   */
+  protected $entityManager;
+
+  /**
+   * Constructs a \Drupal\forum\Form\OverviewForm object.
+   *
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler service.
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   *   The entity manager service.
+   */
+  public function __construct(ModuleHandlerInterface $module_handler, EntityManagerInterface $entity_manager) {
+    parent::__construct($module_handler, $entity_manager);
+    $this->entityManager = $entity_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'forum_overview';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $forum_config = $this->config('forum.settings');
+    $vid = $forum_config->get('vocabulary');
+    $vocabulary = $this->entityManager->getStorage('taxonomy_vocabulary')->load($vid);
+    if (!$vocabulary) {
+      throw new NotFoundHttpException();
+    }
+
+    // Build base taxonomy term overview.
+    $form = parent::buildForm($form, $form_state, $vocabulary);
+
+    foreach (Element::children($form['terms']) as $key) {
+      if (isset($form['terms'][$key]['#term'])) {
+        $term = $form['terms'][$key]['#term'];
+        $form['terms'][$key]['term']['#url'] = Url::fromRoute('forum.page', ['taxonomy_term' => $term->id()]);
+        unset($form['terms'][$key]['operations']['#links']['delete']);
+        $route_parameters = $form['terms'][$key]['operations']['#links']['edit']['url']->getRouteParameters();
+        if (!empty($term->forum_container->value)) {
+          $form['terms'][$key]['operations']['#links']['edit']['title'] = $this->t('edit container');
+          $form['terms'][$key]['operations']['#links']['edit']['url'] = Url::fromRoute('entity.taxonomy_term.forum_edit_container_form', $route_parameters);
+        }
+        else {
+          $form['terms'][$key]['operations']['#links']['edit']['title'] = $this->t('edit forum');
+          $form['terms'][$key]['operations']['#links']['edit']['url'] = Url::fromRoute('entity.taxonomy_term.forum_edit_form', $route_parameters);
+        }
+        // We don't want the redirect from the link so we can redirect the
+        // delete action.
+        unset($form['terms'][$key]['operations']['#links']['edit']['query']['destination']);
+      }
+    }
+
+    // Remove the alphabetical reset.
+    unset($form['actions']['reset_alphabetical']);
+
+    // Use the existing taxonomy overview submit handler.
+    $form['terms']['#empty'] = $this->t('No containers or forums available. <a href=":container">Add container</a> or <a href=":forum">Add forum</a>.', array(
+      ':container' => $this->url('forum.add_container'),
+      ':forum' => $this->url('forum.add_forum')
+    ));
+    return $form;
+  }
+
+}

web/core/modules/forum/src/ForumIndexStorage.php

@@ -0,0 +1,163 @@
+<?php
+
+namespace Drupal\forum;
+use Drupal\comment\CommentInterface;
+use Drupal\Core\Database\Connection;
+use Drupal\node\NodeInterface;
+
+/**
+ * Handles CRUD operations to {forum_index} table.
+ */
+class ForumIndexStorage implements ForumIndexStorageInterface {
+
+  /**
+   * The active database connection.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $database;
+
+  /**
+   * Constructs a ForumIndexStorage object.
+   *
+   * @param \Drupal\Core\Database\Connection $database
+   *   The current database connection.
+   */
+  function __construct(Connection $database) {
+    $this->database = $database;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getOriginalTermId(NodeInterface $node) {
+    return $this->database->queryRange("SELECT f.tid FROM {forum} f INNER JOIN {node} n ON f.vid = n.vid WHERE n.nid = :nid ORDER BY f.vid DESC", 0, 1, array(':nid' => $node->id()))->fetchField();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function create(NodeInterface $node) {
+    $this->database->insert('forum')
+      ->fields(array(
+        'tid' => $node->forum_tid,
+        'vid' => $node->getRevisionId(),
+        'nid' => $node->id(),
+      ))
+      ->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function read(array $vids) {
+    return $this->database->select('forum', 'f')
+      ->fields('f', array('nid', 'tid'))
+      ->condition('f.vid', $vids, 'IN')
+      ->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function delete(NodeInterface $node) {
+    $this->database->delete('forum')
+      ->condition('nid', $node->id())
+      ->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteRevision(NodeInterface $node) {
+    $this->database->delete('forum')
+      ->condition('nid', $node->id())
+      ->condition('vid', $node->getRevisionId())
+      ->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function update(NodeInterface $node) {
+    $this->database->update('forum')
+      ->fields(array('tid' => $node->forum_tid))
+      ->condition('vid', $node->getRevisionId())
+      ->execute();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function updateIndex(NodeInterface $node) {
+    $nid = $node->id();
+    $count = $this->database->query("SELECT COUNT(cid) FROM {comment_field_data} c INNER JOIN {forum_index} i ON c.entity_id = i.nid WHERE c.entity_id = :nid AND c.field_name = 'comment_forum' AND c.entity_type = 'node' AND c.status = :status AND c.default_langcode = 1", array(
+      ':nid' => $nid,
+      ':status' => CommentInterface::PUBLISHED,
+    ))->fetchField();
+
+    if ($count > 0) {
+      // Comments exist.
+      $last_reply = $this->database->queryRange("SELECT cid, name, created, uid FROM {comment_field_data} WHERE entity_id = :nid AND field_name = 'comment_forum' AND entity_type = 'node' AND status = :status AND default_langcode = 1 ORDER BY cid DESC", 0, 1, array(
+        ':nid' => $nid,
+        ':status' => CommentInterface::PUBLISHED,
+      ))->fetchObject();
+      $this->database->update('forum_index')
+        ->fields( array(
+          'comment_count' => $count,
+          'last_comment_timestamp' => $last_reply->created,
+        ))
+        ->condition('nid', $nid)
+        ->execute();
+    }
+    else {
+      // Comments do not exist.
+      // @todo This should be actually filtering on the desired node language
+      $this->database->update('forum_index')
+        ->fields( array(
+          'comment_count' => 0,
+          'last_comment_timestamp' => $node->getCreatedTime(),
+        ))
+        ->condition('nid', $nid)
+        ->execute();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function createIndex(NodeInterface $node) {
+    $query = $this->database->insert('forum_index')
+      ->fields(array('nid', 'title', 'tid', 'sticky', 'created', 'comment_count', 'last_comment_timestamp'));
+    foreach ($node->getTranslationLanguages() as $langcode => $language) {
+      $translation = $node->getTranslation($langcode);
+      foreach ($translation->taxonomy_forums as $item) {
+        $query->values(array(
+          'nid' => $node->id(),
+          'title' => $translation->label(),
+          'tid' => $item->target_id,
+          'sticky' => (int) $node->isSticky(),
+          'created' => $node->getCreatedTime(),
+          'comment_count' => 0,
+          'last_comment_timestamp' => $node->getCreatedTime(),
+        ));
+      }
+    }
+    $query->execute();
+    // The logic for determining last_comment_count is fairly complex, so
+    // update the index too.
+    if ($node->isNew()) {
+      $this->updateIndex($node);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteIndex(NodeInterface $node) {
+    $this->database->delete('forum_index')
+      ->condition('nid', $node->id())
+      ->execute();
+  }
+
+}

web/core/modules/forum/src/ForumIndexStorageInterface.php

@@ -0,0 +1,91 @@
+<?php
+
+namespace Drupal\forum;
+
+use Drupal\node\NodeInterface;
+
+
+/**
+ * Handles CRUD operations to {forum_index} table.
+ */
+interface ForumIndexStorageInterface {
+
+  /**
+   * Returns the forum term id associated with an existing forum node.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   The existing forum node.
+   *
+   * @return int
+   *   The forum term id currently associated with the node.
+   */
+  public function getOriginalTermId(NodeInterface $node);
+
+  /**
+   * Creates a record in {forum} table for the given node.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   The node for which the record is to be created.
+   */
+  public function create(NodeInterface $node);
+
+  /**
+   * Reads an array of {forum} records for the given revision ids.
+   *
+   * @param array $vids
+   *   An array of node revision ids.
+   *
+   * @return \Drupal\Core\Database\StatementInterface
+   *   The records from {forum} for the given vids.
+   */
+  public function read(array $vids);
+
+  /**
+   * Updates the {forum} table for the given node.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   The node for which the record is to be updated.
+   */
+  public function update(NodeInterface $node);
+
+  /**
+   * Deletes the records in {forum} table for the given node.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   The node for which the records are to be deleted.
+   */
+  public function delete(NodeInterface $node);
+
+  /**
+   * Deletes the records in {forum} table for a given node revision.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   The node revision for which the records are to be deleted.
+   */
+  public function deleteRevision(NodeInterface $node);
+
+  /**
+   * Creates a {forum_index} entry for the given node.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   The node for which the index records are to be created.
+   */
+  public function createIndex(NodeInterface $node);
+
+  /**
+   * Updates the {forum_index} records for a given node.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   The node for which the index records are to be updated.
+   */
+  public function updateIndex(NodeInterface $node);
+
+  /**
+   * Deletes the {forum_index} records for a given node.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   The node for which the index records are to be deleted.
+   */
+  public function deleteIndex(NodeInterface $node);
+
+}

web/core/modules/forum/src/ForumManager.php

@@ -0,0 +1,516 @@
+<?php
+
+namespace Drupal\forum;
+
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Database\Connection;
+use Drupal\Core\DependencyInjection\DependencySerializationTrait;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\comment\CommentManagerInterface;
+use Drupal\node\NodeInterface;
+
+/**
+ * Provides forum manager service.
+ */
+class ForumManager implements ForumManagerInterface {
+  use StringTranslationTrait;
+  use DependencySerializationTrait {
+    __wakeup as defaultWakeup;
+    __sleep as defaultSleep;
+  }
+
+  /**
+   * Forum sort order, newest first.
+   */
+  const NEWEST_FIRST = 1;
+
+  /**
+   * Forum sort order, oldest first.
+   */
+  const OLDEST_FIRST = 2;
+
+  /**
+   * Forum sort order, posts with most comments first.
+   */
+  const MOST_POPULAR_FIRST = 3;
+
+  /**
+   * Forum sort order, posts with the least comments first.
+   */
+  const LEAST_POPULAR_FIRST = 4;
+
+  /**
+   * Forum settings config object.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * Entity manager service
+   *
+   * @var \Drupal\Core\Entity\EntityManagerInterface
+   */
+  protected $entityManager;
+
+  /**
+   * Database connection
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * The comment manager service.
+   *
+   * @var \Drupal\comment\CommentManagerInterface
+   */
+  protected $commentManager;
+
+  /**
+   * Array of last post information keyed by forum (term) id.
+   *
+   * @var array
+   */
+  protected $lastPostData = array();
+
+  /**
+   * Array of forum statistics keyed by forum (term) id.
+   *
+   * @var array
+   */
+  protected $forumStatistics = array();
+
+  /**
+   * Array of forum children keyed by parent forum (term) id.
+   *
+   * @var array
+   */
+  protected $forumChildren = array();
+
+  /**
+   * Array of history keyed by nid.
+   *
+   * @var array
+   */
+  protected $history = array();
+
+  /**
+   * Cached forum index.
+   *
+   * @var \Drupal\taxonomy\TermInterface
+   */
+  protected $index;
+
+  /**
+   * Constructs the forum manager service.
+   *
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The config factory service.
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   *   The entity manager service.
+   * @param \Drupal\Core\Database\Connection $connection
+   *   The current database connection.
+   * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
+   *   The translation manager service.
+   * @param \Drupal\comment\CommentManagerInterface $comment_manager
+   *   The comment manager service.
+   */
+  public function __construct(ConfigFactoryInterface $config_factory, EntityManagerInterface $entity_manager, Connection $connection, TranslationInterface $string_translation, CommentManagerInterface $comment_manager) {
+    $this->configFactory = $config_factory;
+    $this->entityManager = $entity_manager;
+    $this->connection = $connection;
+    $this->stringTranslation = $string_translation;
+    $this->commentManager = $comment_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getTopics($tid, AccountInterface $account) {
+    $config = $this->configFactory->get('forum.settings');
+    $forum_per_page = $config->get('topics.page_limit');
+    $sortby = $config->get('topics.order');
+
+    $header = array(
+      array('data' => $this->t('Topic'), 'field' => 'f.title'),
+      array('data' => $this->t('Replies'), 'field' => 'f.comment_count'),
+      array('data' => $this->t('Last reply'), 'field' => 'f.last_comment_timestamp'),
+    );
+
+    $order = $this->getTopicOrder($sortby);
+    for ($i = 0; $i < count($header); $i++) {
+      if ($header[$i]['field'] == $order['field']) {
+        $header[$i]['sort'] = $order['sort'];
+      }
+    }
+
+    $query = $this->connection->select('forum_index', 'f')
+      ->extend('Drupal\Core\Database\Query\PagerSelectExtender')
+      ->extend('Drupal\Core\Database\Query\TableSortExtender');
+    $query->fields('f');
+    $query
+      ->condition('f.tid', $tid)
+      ->addTag('node_access')
+      ->addMetaData('base_table', 'forum_index')
+      ->orderBy('f.sticky', 'DESC')
+      ->orderByHeader($header)
+      ->limit($forum_per_page);
+
+    $count_query = $this->connection->select('forum_index', 'f');
+    $count_query->condition('f.tid', $tid);
+    $count_query->addExpression('COUNT(*)');
+    $count_query->addTag('node_access');
+    $count_query->addMetaData('base_table', 'forum_index');
+
+    $query->setCountQuery($count_query);
+    $result = $query->execute();
+    $nids = array();
+    foreach ($result as $record) {
+      $nids[] = $record->nid;
+    }
+    if ($nids) {
+      $nodes = $this->entityManager->getStorage('node')->loadMultiple($nids);
+
+      $query = $this->connection->select('node_field_data', 'n')
+        ->extend('Drupal\Core\Database\Query\TableSortExtender');
+      $query->fields('n', array('nid'));
+
+      $query->join('comment_entity_statistics', 'ces', "n.nid = ces.entity_id AND ces.field_name = 'comment_forum' AND ces.entity_type = 'node'");
+      $query->fields('ces', array(
+        'cid',
+        'last_comment_uid',
+        'last_comment_timestamp',
+        'comment_count'
+      ));
+
+      $query->join('forum_index', 'f', 'f.nid = n.nid');
+      $query->addField('f', 'tid', 'forum_tid');
+
+      $query->join('users_field_data', 'u', 'n.uid = u.uid AND u.default_langcode = 1');
+      $query->addField('u', 'name');
+
+      $query->join('users_field_data', 'u2', 'ces.last_comment_uid = u2.uid AND u.default_langcode = 1');
+
+      $query->addExpression('CASE ces.last_comment_uid WHEN 0 THEN ces.last_comment_name ELSE u2.name END', 'last_comment_name');
+
+      $query
+        ->orderBy('f.sticky', 'DESC')
+        ->orderByHeader($header)
+        ->condition('n.nid', $nids, 'IN')
+        // @todo This should be actually filtering on the desired node language
+        //   and just fall back to the default language.
+        ->condition('n.default_langcode', 1);
+
+      $result = array();
+      foreach ($query->execute() as $row) {
+        $topic = $nodes[$row->nid];
+        $topic->comment_mode = $topic->comment_forum->status;
+
+        foreach ($row as $key => $value) {
+          $topic->{$key} = $value;
+        }
+        $result[] = $topic;
+      }
+    }
+    else {
+      $result = array();
+    }
+
+    $topics = array();
+    $first_new_found = FALSE;
+    foreach ($result as $topic) {
+      if ($account->isAuthenticated()) {
+        // A forum is new if the topic is new, or if there are new comments since
+        // the user's last visit.
+        if ($topic->forum_tid != $tid) {
+          $topic->new = 0;
+        }
+        else {
+          $history = $this->lastVisit($topic->id(), $account);
+          $topic->new_replies = $this->commentManager->getCountNewComments($topic, 'comment_forum', $history);
+          $topic->new = $topic->new_replies || ($topic->last_comment_timestamp > $history);
+        }
+      }
+      else {
+        // Do not track "new replies" status for topics if the user is anonymous.
+        $topic->new_replies = 0;
+        $topic->new = 0;
+      }
+
+      // Make sure only one topic is indicated as the first new topic.
+      $topic->first_new = FALSE;
+      if ($topic->new != 0 && !$first_new_found) {
+        $topic->first_new = TRUE;
+        $first_new_found = TRUE;
+      }
+
+      if ($topic->comment_count > 0) {
+        $last_reply = new \stdClass();
+        $last_reply->created = $topic->last_comment_timestamp;
+        $last_reply->name = $topic->last_comment_name;
+        $last_reply->uid = $topic->last_comment_uid;
+        $topic->last_reply = $last_reply;
+      }
+      $topics[$topic->id()] = $topic;
+    }
+
+    return array('topics' => $topics, 'header' => $header);
+
+  }
+
+  /**
+   * Gets topic sorting information based on an integer code.
+   *
+   * @param int $sortby
+   *   One of the following integers indicating the sort criteria:
+   *   - ForumManager::NEWEST_FIRST: Date - newest first.
+   *   - ForumManager::OLDEST_FIRST: Date - oldest first.
+   *   - ForumManager::MOST_POPULAR_FIRST: Posts with the most comments first.
+   *   - ForumManager::LEAST_POPULAR_FIRST: Posts with the least comments first.
+   *
+   * @return array
+   *   An array with the following values:
+   *   - field: A field for an SQL query.
+   *   - sort: 'asc' or 'desc'.
+   */
+  protected function getTopicOrder($sortby) {
+    switch ($sortby) {
+      case static::NEWEST_FIRST:
+        return array('field' => 'f.last_comment_timestamp', 'sort' => 'desc');
+
+      case static::OLDEST_FIRST:
+        return array('field' => 'f.last_comment_timestamp', 'sort' => 'asc');
+
+      case static::MOST_POPULAR_FIRST:
+        return array('field' => 'f.comment_count', 'sort' => 'desc');
+
+      case static::LEAST_POPULAR_FIRST:
+        return array('field' => 'f.comment_count', 'sort' => 'asc');
+
+    }
+  }
+
+  /**
+   * Gets the last time the user viewed a node.
+   *
+   * @param int $nid
+   *   The node ID.
+   * @param \Drupal\Core\Session\AccountInterface $account
+   *   Account to fetch last time for.
+   *
+   * @return int
+   *   The timestamp when the user last viewed this node, if the user has
+   *   previously viewed the node; otherwise HISTORY_READ_LIMIT.
+   */
+  protected function lastVisit($nid, AccountInterface $account) {
+    if (empty($this->history[$nid])) {
+      $result = $this->connection->select('history', 'h')
+        ->fields('h', array('nid', 'timestamp'))
+        ->condition('uid', $account->id())
+        ->execute();
+      foreach ($result as $t) {
+        $this->history[$t->nid] = $t->timestamp > HISTORY_READ_LIMIT ? $t->timestamp : HISTORY_READ_LIMIT;
+      }
+    }
+    return isset($this->history[$nid]) ? $this->history[$nid] : HISTORY_READ_LIMIT;
+  }
+
+  /**
+   * Provides the last post information for the given forum tid.
+   *
+   * @param int $tid
+   *   The forum tid.
+   *
+   * @return \stdClass
+   *   The last post for the given forum.
+   */
+  protected function getLastPost($tid) {
+    if (!empty($this->lastPostData[$tid])) {
+      return $this->lastPostData[$tid];
+    }
+    // Query "Last Post" information for this forum.
+    $query = $this->connection->select('node_field_data', 'n');
+    $query->join('forum', 'f', 'n.vid = f.vid AND f.tid = :tid', array(':tid' => $tid));
+    $query->join('comment_entity_statistics', 'ces', "n.nid = ces.entity_id AND ces.field_name = 'comment_forum' AND ces.entity_type = 'node'");
+    $query->join('users_field_data', 'u', 'ces.last_comment_uid = u.uid AND u.default_langcode = 1');
+    $query->addExpression('CASE ces.last_comment_uid WHEN 0 THEN ces.last_comment_name ELSE u.name END', 'last_comment_name');
+
+    $topic = $query
+      ->fields('ces', array('last_comment_timestamp', 'last_comment_uid'))
+      ->condition('n.status', 1)
+      ->orderBy('last_comment_timestamp', 'DESC')
+      ->range(0, 1)
+      ->addTag('node_access')
+      ->execute()
+      ->fetchObject();
+
+    // Build the last post information.
+    $last_post = new \stdClass();
+    if (!empty($topic->last_comment_timestamp)) {
+      $last_post->created = $topic->last_comment_timestamp;
+      $last_post->name = $topic->last_comment_name;
+      $last_post->uid = $topic->last_comment_uid;
+    }
+
+    $this->lastPostData[$tid] = $last_post;
+    return $last_post;
+  }
+
+  /**
+   * Provides statistics for a forum.
+   *
+   * @param int $tid
+   *   The forum tid.
+   *
+   * @return \stdClass|null
+   *   Statistics for the given forum if statistics exist, else NULL.
+   */
+  protected function getForumStatistics($tid) {
+    if (empty($this->forumStatistics)) {
+      // Prime the statistics.
+      $query = $this->connection->select('node_field_data', 'n');
+      $query->join('comment_entity_statistics', 'ces', "n.nid = ces.entity_id AND ces.field_name = 'comment_forum' AND ces.entity_type = 'node'");
+      $query->join('forum', 'f', 'n.vid = f.vid');
+      $query->addExpression('COUNT(n.nid)', 'topic_count');
+      $query->addExpression('SUM(ces.comment_count)', 'comment_count');
+      $this->forumStatistics = $query
+        ->fields('f', array('tid'))
+        ->condition('n.status', 1)
+        ->condition('n.default_langcode', 1)
+        ->groupBy('tid')
+        ->addTag('node_access')
+        ->execute()
+        ->fetchAllAssoc('tid');
+    }
+
+    if (!empty($this->forumStatistics[$tid])) {
+      return $this->forumStatistics[$tid];
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getChildren($vid, $tid) {
+    if (!empty($this->forumChildren[$tid])) {
+      return $this->forumChildren[$tid];
+    }
+    $forums = array();
+    $_forums = $this->entityManager->getStorage('taxonomy_term')->loadTree($vid, $tid, NULL, TRUE);
+    foreach ($_forums as $forum) {
+      // Merge in the topic and post counters.
+      if (($count = $this->getForumStatistics($forum->id()))) {
+        $forum->num_topics = $count->topic_count;
+        $forum->num_posts = $count->topic_count + $count->comment_count;
+      }
+      else {
+        $forum->num_topics = 0;
+        $forum->num_posts = 0;
+      }
+
+      // Merge in last post details.
+      $forum->last_post = $this->getLastPost($forum->id());
+      $forums[$forum->id()] = $forum;
+    }
+
+    $this->forumChildren[$tid] = $forums;
+    return $forums;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIndex() {
+    if ($this->index) {
+      return $this->index;
+    }
+
+    $vid = $this->configFactory->get('forum.settings')->get('vocabulary');
+    $index = $this->entityManager->getStorage('taxonomy_term')->create(array(
+      'tid' => 0,
+      'container' => 1,
+      'parents' => array(),
+      'isIndex' => TRUE,
+      'vid' => $vid
+    ));
+
+    // Load the tree below.
+    $index->forums = $this->getChildren($vid, 0);
+    $this->index = $index;
+    return $index;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function resetCache() {
+    // Reset the index.
+    $this->index = NULL;
+    // Reset history.
+    $this->history = array();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getParents($tid) {
+    return $this->entityManager->getStorage('taxonomy_term')->loadAllParents($tid);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function checkNodeType(NodeInterface $node) {
+    // Fetch information about the forum field.
+    $field_definitions = $this->entityManager->getFieldDefinitions('node', $node->bundle());
+    return !empty($field_definitions['taxonomy_forums']);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function unreadTopics($term, $uid) {
+    $query = $this->connection->select('node_field_data', 'n');
+    $query->join('forum', 'f', 'n.vid = f.vid AND f.tid = :tid', array(':tid' => $term));
+    $query->leftJoin('history', 'h', 'n.nid = h.nid AND h.uid = :uid', array(':uid' => $uid));
+    $query->addExpression('COUNT(n.nid)', 'count');
+    return $query
+      ->condition('status', 1)
+      // @todo This should be actually filtering on the desired node status
+      //   field language and just fall back to the default language.
+      ->condition('n.default_langcode', 1)
+      ->condition('n.created', HISTORY_READ_LIMIT, '>')
+      ->isNull('h.nid')
+      ->addTag('node_access')
+      ->execute()
+      ->fetchField();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __sleep() {
+    $vars = $this->defaultSleep();
+    // Do not serialize static cache.
+    unset($vars['history'], $vars['index'], $vars['lastPostData'], $vars['forumChildren'], $vars['forumStatistics']);
+    return $vars;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __wakeup() {
+    $this->defaultWakeup();
+    // Initialize static cache.
+    $this->history = array();
+    $this->lastPostData = array();
+    $this->forumChildren = array();
+    $this->forumStatistics = array();
+    $this->index = NULL;
+  }
+
+}

web/core/modules/forum/src/ForumManagerInterface.php

@@ -0,0 +1,94 @@
+<?php
+
+namespace Drupal\forum;
+
+use Drupal\Core\Session\AccountInterface;
+use Drupal\node\NodeInterface;
+
+/**
+ * Provides forum manager interface.
+ */
+interface ForumManagerInterface {
+
+  /**
+   * Gets list of forum topics.
+   *
+   * @param int $tid
+   *   Term ID.
+   * @param \Drupal\Core\Session\AccountInterface $account
+   *   Account to fetch topics for.
+   *
+   * @return array
+   *   Array with keys 'topics' and 'header'.
+   */
+  public function getTopics($tid, AccountInterface $account);
+
+  /**
+   * Utility method to fetch the child forums for a given forum.
+   *
+   * @param int $vid
+   *   The forum vocabulary ID.
+   * @param int $tid
+   *   The forum ID to fetch the children for.
+   *
+   * @return array
+   *   Array of children.
+   */
+  public function getChildren($vid, $tid);
+
+  /**
+   * Generates and returns the forum index.
+   *
+   * The forum index is a pseudo term that provides an overview of all forums.
+   *
+   * @return \Drupal\taxonomy\TermInterface
+   *   A pseudo term representing the overview of all forums.
+   */
+  public function getIndex();
+
+  /**
+   * Resets the ForumManager index and history.
+   */
+  public function resetCache();
+
+  /**
+   * Fetches the parent forums for a given forum.
+   *
+   * @param int $tid
+   *   Term ID.
+   *
+   * @return array
+   *   Array of parent terms.
+   *
+   * @deprecated Scheduled to be removed in 9.0.x, see
+   *   https://www.drupal.org/node/2371593.
+   */
+  public function getParents($tid);
+
+  /**
+   * Checks whether a node can be used in a forum, based on its content type.
+   *
+   * @param \Drupal\node\NodeInterface $node
+   *   A node entity.
+   *
+   * @return bool
+   *   Boolean indicating if the node can be assigned to a forum.
+   */
+  public function checkNodeType(NodeInterface $node);
+
+  /**
+   * Calculates the number of new posts in a forum that the user has not yet read.
+   *
+   * Nodes are new if they are newer than HISTORY_READ_LIMIT.
+   *
+   * @param int $term
+   *   The term ID of the forum.
+   * @param int $uid
+   *   The user ID.
+   *
+   * @return
+   *   The number of new posts in the forum that have not been read by the user.
+   */
+  public function unreadTopics($term, $uid);
+
+}

web/core/modules/forum/src/ForumSettingsForm.php

@@ -0,0 +1,79 @@
+<?php
+
+namespace Drupal\forum;
+
+use Drupal\Core\Form\ConfigFormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Configure forum settings for this site.
+ */
+class ForumSettingsForm extends ConfigFormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'forum_admin_settings';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEditableConfigNames() {
+    return ['forum.settings'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $config = $this->config('forum.settings');
+
+    $options = array(5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 80, 100, 150, 200, 250, 300, 350, 400, 500);
+    $form['forum_hot_topic'] = array(
+      '#type' => 'select',
+      '#title' => $this->t('Hot topic threshold'),
+      '#default_value' => $config->get('topics.hot_threshold'),
+      '#options' => array_combine($options, $options),
+      '#description' => $this->t('The number of replies a topic must have to be considered "hot".'),
+    );
+    $options = array(10, 25, 50, 75, 100);
+    $form['forum_per_page'] = array(
+      '#type' => 'select',
+      '#title' => $this->t('Topics per page'),
+      '#default_value' => $config->get('topics.page_limit'),
+      '#options' => array_combine($options, $options),
+      '#description' => $this->t('Default number of forum topics displayed per page.'),
+    );
+    $forder = array(
+      1 => $this->t('Date - newest first'),
+      2 => $this->t('Date - oldest first'),
+      3 => $this->t('Posts - most active first'),
+      4 => $this->t('Posts - least active first')
+    );
+    $form['forum_order'] = array(
+      '#type' => 'radios',
+      '#title' => $this->t('Default order'),
+      '#default_value' => $config->get('topics.order'),
+      '#options' => $forder,
+      '#description' => $this->t('Default display order for topics.'),
+    );
+
+    return parent::buildForm($form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $this->config('forum.settings')
+      ->set('topics.hot_threshold', $form_state->getValue('forum_hot_topic'))
+      ->set('topics.page_limit', $form_state->getValue('forum_per_page'))
+      ->set('topics.order', $form_state->getValue('forum_order'))
+      ->save();
+
+    parent::submitForm($form, $form_state);
+  }
+
+}

web/core/modules/forum/src/ForumUninstallValidator.php

@@ -0,0 +1,134 @@
+<?php
+
+namespace Drupal\forum;
+
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\Query\QueryFactory;
+use Drupal\Core\Extension\ModuleUninstallValidatorInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\taxonomy\VocabularyInterface;
+
+/**
+ * Prevents forum module from being uninstalled whilst any forum nodes exist
+ * or there are any terms in the forum vocabulary.
+ */
+class ForumUninstallValidator implements ModuleUninstallValidatorInterface {
+
+  use StringTranslationTrait;
+
+  /**
+   * The field storage config storage.
+   *
+   * @var \Drupal\Core\Config\Entity\ConfigEntityStorageInterface
+   */
+  protected $vocabularyStorage;
+
+  /**
+   * The entity query factory.
+   *
+   * @var \Drupal\Core\Entity\Query\QueryFactory
+   */
+  protected $queryFactory;
+
+  /**
+   * The config factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * Constructs a new ForumUninstallValidator.
+   *
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   *   The entity manager.
+   * @param \Drupal\Core\Entity\Query\QueryFactory $query_factory
+   *   The entity query factory.
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The config factory.
+   * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
+   *   The string translation service.
+   */
+  public function __construct(EntityManagerInterface $entity_manager, QueryFactory $query_factory, ConfigFactoryInterface $config_factory, TranslationInterface $string_translation) {
+    $this->vocabularyStorage = $entity_manager->getStorage('taxonomy_vocabulary');
+    $this->queryFactory = $query_factory;
+    $this->configFactory = $config_factory;
+    $this->stringTranslation = $string_translation;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validate($module) {
+    $reasons = [];
+    if ($module == 'forum') {
+      if ($this->hasForumNodes()) {
+        $reasons[] = $this->t('To uninstall Forum, first delete all <em>Forum</em> content');
+      }
+
+      $vocabulary = $this->getForumVocabulary();
+      if ($this->hasTermsForVocabulary($vocabulary)) {
+        if ($vocabulary->access('view')) {
+          $reasons[] = $this->t('To uninstall Forum, first delete all <a href=":url">%vocabulary</a> terms', [
+            '%vocabulary' => $vocabulary->label(),
+            ':url' => $vocabulary->url('overview-form'),
+          ]);
+        }
+        else {
+          $reasons[] = $this->t('To uninstall Forum, first delete all %vocabulary terms', [
+            '%vocabulary' => $vocabulary->label()
+          ]);
+        }
+      }
+    }
+
+    return $reasons;
+  }
+
+  /**
+   * Determines if there are any forum nodes or not.
+   *
+   * @return bool
+   *   TRUE if there are forum nodes, FALSE otherwise.
+   */
+  protected function hasForumNodes() {
+    $nodes = $this->queryFactory->get('node')
+      ->condition('type', 'forum')
+      ->accessCheck(FALSE)
+      ->range(0, 1)
+      ->execute();
+    return !empty($nodes);
+  }
+
+  /**
+   * Determines if there are any taxonomy terms for a specified vocabulary.
+   *
+   * @param \Drupal\taxonomy\VocabularyInterface $vocabulary
+   *   The vocabulary to check for terms.
+   *
+   * @return bool
+   *   TRUE if there are terms for this vocabulary, FALSE otherwise.
+   */
+  protected function hasTermsForVocabulary(VocabularyInterface $vocabulary) {
+    $terms = $this->queryFactory->get('taxonomy_term')
+      ->condition('vid', $vocabulary->id())
+      ->accessCheck(FALSE)
+      ->range(0, 1)
+      ->execute();
+    return !empty($terms);
+  }
+
+  /**
+   * Returns the vocabulary configured for forums.
+   *
+   * @return \Drupal\taxonomy\VocabularyInterface
+   *   The vocabulary entity for forums.
+   */
+  protected function getForumVocabulary() {
+    $vid = $this->configFactory->get('forum.settings')->get('vocabulary');
+    return $this->vocabularyStorage->load($vid);
+  }
+
+}

web/core/modules/forum/src/Plugin/Block/ActiveTopicsBlock.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Drupal\forum\Plugin\Block;
+
+/**
+ * Provides an 'Active forum topics' block.
+ *
+ * @Block(
+ *   id = "forum_active_block",
+ *   admin_label = @Translation("Active forum topics"),
+ *   category = @Translation("Lists (Views)")
+ * )
+ */
+class ActiveTopicsBlock extends ForumBlockBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function buildForumQuery() {
+    return db_select('forum_index', 'f')
+      ->fields('f')
+      ->addTag('node_access')
+      ->addMetaData('base_table', 'forum_index')
+      ->orderBy('f.last_comment_timestamp', 'DESC')
+      ->range(0, $this->configuration['block_count']);
+  }
+
+}

web/core/modules/forum/src/Plugin/Block/ForumBlockBase.php

@@ -0,0 +1,96 @@
+<?php
+
+namespace Drupal\forum\Plugin\Block;
+
+use Drupal\Core\Access\AccessResult;
+use Drupal\Core\Block\BlockBase;
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\Url;
+
+/**
+ * Provides a base class for Forum blocks.
+ */
+abstract class ForumBlockBase extends BlockBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build() {
+    $result = $this->buildForumQuery()->execute();
+    $elements = array();
+    if ($node_title_list = node_title_list($result)) {
+      $elements['forum_list'] = $node_title_list;
+      $elements['forum_more'] = array(
+        '#type' => 'more_link',
+        '#url' => Url::fromRoute('forum.index'),
+        '#attributes' => array('title' => $this->t('Read the latest forum topics.')),
+      );
+    }
+    return $elements;
+  }
+
+  /**
+   * Builds the select query to use for this forum block.
+   *
+   * @return \Drupal\Core\Database\Query\Select
+   *   A Select object.
+   */
+  abstract protected function buildForumQuery();
+
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultConfiguration() {
+    return array(
+      'properties' => array(
+        'administrative' => TRUE,
+      ),
+      'block_count' => 5,
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function blockAccess(AccountInterface $account) {
+    return AccessResult::allowedIfHasPermission($account, 'access content');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function blockForm($form, FormStateInterface $form_state) {
+    $range = range(2, 20);
+    $form['block_count'] = array(
+      '#type' => 'select',
+      '#title' => $this->t('Number of topics'),
+      '#default_value' => $this->configuration['block_count'],
+      '#options' => array_combine($range, $range),
+    );
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function blockSubmit($form, FormStateInterface $form_state) {
+    $this->configuration['block_count'] = $form_state->getValue('block_count');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheContexts() {
+    return Cache::mergeContexts(parent::getCacheContexts(), ['user.node_grants:view']);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheTags() {
+    return Cache::mergeTags(parent::getCacheTags(), ['node_list']);
+  }
+
+}

web/core/modules/forum/src/Plugin/Block/NewTopicsBlock.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Drupal\forum\Plugin\Block;
+
+/**
+ * Provides a 'New forum topics' block.
+ *
+ * @Block(
+ *   id = "forum_new_block",
+ *   admin_label = @Translation("New forum topics"),
+ *   category = @Translation("Lists (Views)")
+ * )
+ */
+class NewTopicsBlock extends ForumBlockBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function buildForumQuery() {
+    return db_select('forum_index', 'f')
+      ->fields('f')
+      ->addTag('node_access')
+      ->addMetaData('base_table', 'forum_index')
+      ->orderBy('f.created', 'DESC')
+      ->range(0, $this->configuration['block_count']);
+  }
+
+}

web/core/modules/forum/src/Plugin/Validation/Constraint/ForumLeafConstraint.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Drupal\forum\Plugin\Validation\Constraint;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Checks that the node is assigned only a "leaf" term in the forum taxonomy.
+ *
+ * @Constraint(
+ *   id = "ForumLeaf",
+ *   label = @Translation("Forum leaf", context = "Validation"),
+ * )
+ */
+class ForumLeafConstraint extends Constraint {
+
+  public $selectForum = 'Select a forum.';
+  public $noLeafMessage = 'The item %forum is a forum container, not a forum. Select one of the forums below instead.';
+
+}

web/core/modules/forum/src/Plugin/Validation/Constraint/ForumLeafConstraintValidator.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace Drupal\forum\Plugin\Validation\Constraint;
+
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+
+/**
+ * Validates the ForumLeaf constraint.
+ */
+class ForumLeafConstraintValidator extends ConstraintValidator {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validate($items, Constraint $constraint) {
+    $item = $items->first();
+    if (!isset($item)) {
+      return NULL;
+    }
+
+    // Verify that a term has been selected.
+    if (!$item->entity) {
+      $this->context->addViolation($constraint->selectForum);
+    }
+
+    // The forum_container flag must not be set.
+    if (!empty($item->entity->forum_container->value)) {
+      $this->context->addViolation($constraint->noLeafMessage, array('%forum' => $item->entity->getName()));
+    }
+  }
+
+}

web/core/modules/forum/src/ProxyClass/ForumUninstallValidator.php

@@ -0,0 +1,88 @@
+<?php
+// @codingStandardsIgnoreFile
+
+/**
+ * This file was generated via php core/scripts/generate-proxy-class.php 'Drupal\forum\ForumUninstallValidator' "core/modules/forum/src".
+ */
+
+namespace Drupal\forum\ProxyClass {
+
+    /**
+     * Provides a proxy class for \Drupal\forum\ForumUninstallValidator.
+     *
+     * @see \Drupal\Component\ProxyBuilder
+     */
+    class ForumUninstallValidator implements \Drupal\Core\Extension\ModuleUninstallValidatorInterface
+    {
+
+        use \Drupal\Core\DependencyInjection\DependencySerializationTrait;
+
+        /**
+         * The id of the original proxied service.
+         *
+         * @var string
+         */
+        protected $drupalProxyOriginalServiceId;
+
+        /**
+         * The real proxied service, after it was lazy loaded.
+         *
+         * @var \Drupal\forum\ForumUninstallValidator
+         */
+        protected $service;
+
+        /**
+         * The service container.
+         *
+         * @var \Symfony\Component\DependencyInjection\ContainerInterface
+         */
+        protected $container;
+
+        /**
+         * Constructs a ProxyClass Drupal proxy object.
+         *
+         * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
+         *   The container.
+         * @param string $drupal_proxy_original_service_id
+         *   The service ID of the original service.
+         */
+        public function __construct(\Symfony\Component\DependencyInjection\ContainerInterface $container, $drupal_proxy_original_service_id)
+        {
+            $this->container = $container;
+            $this->drupalProxyOriginalServiceId = $drupal_proxy_original_service_id;
+        }
+
+        /**
+         * Lazy loads the real service from the container.
+         *
+         * @return object
+         *   Returns the constructed real service.
+         */
+        protected function lazyLoadItself()
+        {
+            if (!isset($this->service)) {
+                $this->service = $this->container->get($this->drupalProxyOriginalServiceId);
+            }
+
+            return $this->service;
+        }
+
+        /**
+         * {@inheritdoc}
+         */
+        public function validate($module)
+        {
+            return $this->lazyLoadItself()->validate($module);
+        }
+
+        /**
+         * {@inheritdoc}
+         */
+        public function setStringTranslation(\Drupal\Core\StringTranslation\TranslationInterface $translation)
+        {
+            return $this->lazyLoadItself()->setStringTranslation($translation);
+        }
+
+    }
+
+}

web/core/modules/forum/src/Tests/ForumBlockTest.php

@@ -0,0 +1,180 @@
+<?php
+
+namespace Drupal\forum\Tests;
+
+use Drupal\simpletest\WebTestBase;
+use Drupal\Core\Datetime\DrupalDateTime;
+use Drupal\comment\Entity\Comment;
+
+/**
+ * Tests the forum blocks.
+ *
+ * @group forum
+ */
+class ForumBlockTest extends WebTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('forum', 'block');
+
+  /**
+   * A user with various administrative privileges.
+   */
+  protected $adminUser;
+
+  protected function setUp() {
+    parent::setUp();
+
+    // Create users.
+    $this->adminUser = $this->drupalCreateUser(array(
+      'access administration pages',
+      'administer blocks',
+      'administer nodes',
+      'create forum content',
+      'post comments',
+      'skip comment approval',
+    ));
+  }
+
+  /**
+   * Tests the "New forum topics" block.
+   */
+  public function testNewForumTopicsBlock() {
+    $this->drupalLogin($this->adminUser);
+
+    // Enable the new forum topics block.
+    $block = $this->drupalPlaceBlock('forum_new_block');
+    $this->drupalGet('');
+
+    // Create 5 forum topics.
+    $topics = $this->createForumTopics();
+
+
+    $this->assertLink(t('More'), 0, 'New forum topics block has a "more"-link.');
+    $this->assertLinkByHref('forum', 0, 'New forum topics block has a "more"-link.');
+
+    // We expect all 5 forum topics to appear in the "New forum topics" block.
+    foreach ($topics as $topic) {
+      $this->assertLink($topic, 0, format_string('Forum topic @topic found in the "New forum topics" block.', array('@topic' => $topic)));
+    }
+
+    // Configure the new forum topics block to only show 2 topics.
+    $block->getPlugin()->setConfigurationValue('block_count', 2);
+    $block->save();
+
+    $this->drupalGet('');
+    // We expect only the 2 most recent forum topics to appear in the "New forum
+    // topics" block.
+    for ($index = 0; $index < 5; $index++) {
+      if (in_array($index, array(3, 4))) {
+        $this->assertLink($topics[$index], 0, format_string('Forum topic @topic found in the "New forum topics" block.', array('@topic' => $topics[$index])));
+      }
+      else {
+        $this->assertNoText($topics[$index], format_string('Forum topic @topic not found in the "New forum topics" block.', array('@topic' => $topics[$index])));
+      }
+    }
+  }
+
+  /**
+   * Tests the "Active forum topics" block.
+   */
+  public function testActiveForumTopicsBlock() {
+    $this->drupalLogin($this->adminUser);
+
+    // Create 10 forum topics.
+    $topics = $this->createForumTopics(10);
+
+    // Comment on the first 5 topics.
+    $date = new DrupalDateTime();
+    for ($index = 0; $index < 5; $index++) {
+      // Get the node from the topic title.
+      $node = $this->drupalGetNodeByTitle($topics[$index]);
+      $date->modify('+1 minute');
+      $comment = Comment::create(array(
+        'entity_id' => $node->id(),
+        'field_name' => 'comment_forum',
+        'entity_type' => 'node',
+        'node_type' => 'node_type_' . $node->bundle(),
+        'subject' => $this->randomString(20),
+        'comment_body' => $this->randomString(256),
+        'created' => $date->getTimestamp(),
+      ));
+      $comment->save();
+    }
+
+    // Enable the block.
+    $block = $this->drupalPlaceBlock('forum_active_block');
+    $this->drupalGet('');
+    $this->assertLink(t('More'), 0, 'Active forum topics block has a "more"-link.');
+    $this->assertLinkByHref('forum', 0, 'Active forum topics block has a "more"-link.');
+
+    // We expect the first 5 forum topics to appear in the "Active forum topics"
+    // block.
+    $this->drupalGet('<front>');
+    for ($index = 0; $index < 10; $index++) {
+      if ($index < 5) {
+        $this->assertLink($topics[$index], 0, format_string('Forum topic @topic found in the "Active forum topics" block.', array('@topic' => $topics[$index])));
+      }
+      else {
+        $this->assertNoText($topics[$index], format_string('Forum topic @topic not found in the "Active forum topics" block.', array('@topic' => $topics[$index])));
+      }
+    }
+
+    // Configure the active forum block to only show 2 topics.
+    $block->getPlugin()->setConfigurationValue('block_count', 2);
+    $block->save();
+
+    $this->drupalGet('');
+
+    // We expect only the 2 forum topics with most recent comments to appear in
+    // the "Active forum topics" block.
+    for ($index = 0; $index < 10; $index++) {
+      if (in_array($index, array(3, 4))) {
+        $this->assertLink($topics[$index], 0, 'Forum topic found in the "Active forum topics" block.');
+      }
+      else {
+        $this->assertNoText($topics[$index], 'Forum topic not found in the "Active forum topics" block.');
+      }
+    }
+  }
+
+  /**
+   * Creates a forum topic.
+   *
+   * @return string
+   *   The title of the newly generated topic.
+   */
+  protected function createForumTopics($count = 5) {
+    $topics = array();
+    $date = new DrupalDateTime();
+    $date->modify('-24 hours');
+
+    for ($index = 0; $index < $count; $index++) {
+      // Generate a random subject/body.
+      $title = $this->randomMachineName(20);
+      $body = $this->randomMachineName(200);
+      // Forum posts are ordered by timestamp, so force a unique timestamp by
+      // changing the date.
+      $date->modify('+1 minute');
+
+      $edit = array(
+        'title[0][value]' => $title,
+        'body[0][value]' => $body,
+        // Forum posts are ordered by timestamp, so force a unique timestamp by
+        // adding the index.
+        'created[0][value][date]' => $date->format('Y-m-d'),
+        'created[0][value][time]' => $date->format('H:i:s'),
+      );
+
+      // Create the forum topic, preselecting the forum ID via a URL parameter.
+      $this->drupalPostForm('node/add/forum', $edit, t('Save and publish'), array('query' => array('forum_id' => 1)));
+      $topics[] = $title;
+    }
+
+    return $topics;
+  }
+
+}

web/core/modules/forum/src/Tests/ForumIndexTest.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace Drupal\forum\Tests;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests the forum index listing.
+ *
+ * @group forum
+ */
+class ForumIndexTest extends WebTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('taxonomy', 'comment', 'forum');
+
+  protected function setUp() {
+    parent::setUp();
+
+    // Create a test user.
+    $web_user = $this->drupalCreateUser(['create forum content', 'edit own forum content', 'edit any forum content', 'administer nodes', 'administer forums']);
+    $this->drupalLogin($web_user);
+  }
+
+  /**
+   * Tests the forum index for published and unpublished nodes.
+   */
+  function testForumIndexStatus() {
+    // The forum ID to use.
+    $tid = 1;
+
+    // Create a test node.
+    $title = $this->randomMachineName(20);
+    $edit = array(
+      'title[0][value]' => $title,
+      'body[0][value]' => $this->randomMachineName(200),
+    );
+
+    // Create the forum topic, preselecting the forum ID via a URL parameter.
+    $this->drupalGet("forum/$tid");
+    $this->clickLink(t('Add new @node_type', array('@node_type' => 'Forum topic')));
+    $this->assertUrl('node/add/forum', array('query' => array('forum_id' => $tid)));
+    $this->drupalPostForm(NULL, $edit, t('Save and publish'));
+
+    // Check that the node exists in the database.
+    $node = $this->drupalGetNodeByTitle($title);
+    $this->assertTrue(!empty($node), 'New forum node found in database.');
+
+    // Create a child forum.
+    $edit = array(
+      'name[0][value]' => $this->randomMachineName(20),
+      'description[0][value]' => $this->randomMachineName(200),
+      'parent[0]' => $tid,
+    );
+    $this->drupalPostForm('admin/structure/forum/add/forum', $edit, t('Save'));
+    $tid_child = $tid + 1;
+
+    // Verify that the node appears on the index.
+    $this->drupalGet('forum/' . $tid);
+    $this->assertText($title, 'Published forum topic appears on index.');
+    $this->assertCacheTag('node_list');
+    $this->assertCacheTag('config:node.type.forum');
+    $this->assertCacheTag('comment_list');
+    $this->assertCacheTag('node:' . $node->id());
+    $this->assertCacheTag('taxonomy_term:' . $tid);
+    $this->assertCacheTag('taxonomy_term:' . $tid_child);
+
+
+    // Unpublish the node.
+    $this->drupalPostForm('node/' . $node->id() . '/edit', array(), t('Save and unpublish'));
+    $this->drupalGet('node/' . $node->id());
+    $this->assertText(t('Access denied'), 'Unpublished node is no longer accessible.');
+
+    // Verify that the node no longer appears on the index.
+    $this->drupalGet('forum/' . $tid);
+    $this->assertNoText($title, 'Unpublished forum topic no longer appears on index.');
+  }
+
+}

web/core/modules/forum/src/Tests/ForumNodeAccessTest.php

@@ -0,0 +1,86 @@
+<?php
+
+namespace Drupal\forum\Tests;
+
+use Drupal\simpletest\WebTestBase;
+use Drupal\node\Entity\NodeType;
+
+/**
+ * Tests forum block view for private node access.
+ *
+ * @group forum
+ */
+class ForumNodeAccessTest extends WebTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('node', 'comment', 'forum', 'taxonomy', 'tracker', 'node_access_test', 'block');
+
+  protected function setUp() {
+    parent::setUp();
+    node_access_rebuild();
+    node_access_test_add_field(NodeType::load('forum'));
+    \Drupal::state()->set('node_access_test.private', TRUE);
+  }
+
+  /**
+   * Creates some users and creates a public node and a private node.
+   *
+   * Adds both active forum topics and new forum topics blocks to the sidebar.
+   * Tests to ensure private node/public node access is respected on blocks.
+   */
+  function testForumNodeAccess() {
+    // Create some users.
+    $access_user = $this->drupalCreateUser(array('node test view'));
+    $no_access_user = $this->drupalCreateUser();
+    $admin_user = $this->drupalCreateUser(array('access administration pages', 'administer modules', 'administer blocks', 'create forum content'));
+
+    $this->drupalLogin($admin_user);
+
+    // Create a private node.
+    $private_node_title = $this->randomMachineName(20);
+    $edit = array(
+      'title[0][value]' => $private_node_title,
+      'body[0][value]' => $this->randomMachineName(200),
+      'private[0][value]' => TRUE,
+    );
+    $this->drupalPostForm('node/add/forum', $edit, t('Save'), array('query' => array('forum_id' => 1)));
+    $private_node = $this->drupalGetNodeByTitle($private_node_title);
+    $this->assertTrue(!empty($private_node), 'New private forum node found in database.');
+
+    // Create a public node.
+    $public_node_title = $this->randomMachineName(20);
+    $edit = array(
+      'title[0][value]' => $public_node_title,
+      'body[0][value]' => $this->randomMachineName(200),
+    );
+    $this->drupalPostForm('node/add/forum', $edit, t('Save'), array('query' => array('forum_id' => 1)));
+    $public_node = $this->drupalGetNodeByTitle($public_node_title);
+    $this->assertTrue(!empty($public_node), 'New public forum node found in database.');
+
+
+    // Enable the new and active forum blocks.
+    $this->drupalPlaceBlock('forum_active_block');
+    $this->drupalPlaceBlock('forum_new_block');
+
+    // Test for $access_user.
+    $this->drupalLogin($access_user);
+    $this->drupalGet('');
+
+    // Ensure private node and public node are found.
+    $this->assertText($private_node->getTitle(), 'Private node found in block by $access_user');
+    $this->assertText($public_node->getTitle(), 'Public node found in block by $access_user');
+
+    // Test for $no_access_user.
+    $this->drupalLogin($no_access_user);
+    $this->drupalGet('');
+
+    // Ensure private node is not found but public is found.
+    $this->assertNoText($private_node->getTitle(), 'Private node not found in block by $no_access_user');
+    $this->assertText($public_node->getTitle(), 'Public node found in block by $no_access_user');
+  }
+
+}

web/core/modules/forum/src/Tests/ForumTest.php

@@ -0,0 +1,689 @@
+<?php
+
+namespace Drupal\forum\Tests;
+
+use Drupal\Core\Entity\Entity\EntityFormDisplay;
+use Drupal\Core\Entity\Entity\EntityViewDisplay;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Link;
+use Drupal\simpletest\WebTestBase;
+use Drupal\Core\Url;
+use Drupal\taxonomy\Entity\Vocabulary;
+
+/**
+ * Tests for forum.module.
+ *
+ * Create, view, edit, delete, and change forum entries and verify its
+ * consistency in the database.
+ *
+ * @group forum
+ */
+class ForumTest extends WebTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('taxonomy', 'comment', 'forum', 'node', 'block', 'menu_ui', 'help');
+
+  /**
+   * A user with various administrative privileges.
+   */
+  protected $adminUser;
+
+  /**
+   * A user that can create forum topics and edit its own topics.
+   */
+  protected $editOwnTopicsUser;
+
+  /**
+   * A user that can create, edit, and delete forum topics.
+   */
+  protected $editAnyTopicsUser;
+
+  /**
+   * A user with no special privileges.
+   */
+  protected $webUser;
+
+  /**
+   * An administrative user who can bypass comment approval.
+   */
+  protected $postCommentUser;
+
+  /**
+   * An array representing a forum container.
+   */
+  protected $forumContainer;
+
+  /**
+   * An array representing a forum.
+   */
+  protected $forum;
+
+  /**
+   * An array representing a root forum.
+   */
+  protected $rootForum;
+
+  /**
+   * An array of forum topic node IDs.
+   */
+  protected $nids;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->drupalPlaceBlock('system_breadcrumb_block');
+    $this->drupalPlaceBlock('page_title_block');
+
+    // Create users.
+    $this->adminUser = $this->drupalCreateUser(array(
+      'access administration pages',
+      'administer modules',
+      'administer blocks',
+      'administer forums',
+      'administer menu',
+      'administer taxonomy',
+      'create forum content',
+      'access comments',
+    ));
+    $this->editAnyTopicsUser = $this->drupalCreateUser(array(
+      'access administration pages',
+      'create forum content',
+      'edit any forum content',
+      'delete any forum content',
+    ));
+    $this->editOwnTopicsUser = $this->drupalCreateUser(array(
+      'create forum content',
+      'edit own forum content',
+      'delete own forum content',
+    ));
+    $this->webUser = $this->drupalCreateUser();
+    $this->postCommentUser = $this->drupalCreateUser(array(
+      'administer content types',
+      'create forum content',
+      'post comments',
+      'skip comment approval',
+      'access comments',
+    ));
+    $this->drupalPlaceBlock('help_block', array('region' => 'help'));
+    $this->drupalPlaceBlock('local_actions_block');
+  }
+
+  /**
+   * Tests forum functionality through the admin and user interfaces.
+   */
+  function testForum() {
+    //Check that the basic forum install creates a default forum topic
+    $this->drupalGet('/forum');
+    // Look for the "General discussion" default forum
+    $this->assertRaw(Link::createFromRoute(t('General discussion'), 'forum.page', ['taxonomy_term' => 1])->toString(), "Found the default forum at the /forum listing");
+    // Check the presence of expected cache tags.
+    $this->assertCacheTag('config:forum.settings');
+
+    $this->drupalGet(Url::fromRoute('forum.page', ['taxonomy_term' => 1]));
+    $this->assertCacheTag('config:forum.settings');
+
+    // Do the admin tests.
+    $this->doAdminTests($this->adminUser);
+
+    // Check display order.
+    $display = EntityViewDisplay::load('node.forum.default');
+    $body = $display->getComponent('body');
+    $comment = $display->getComponent('comment_forum');
+    $taxonomy = $display->getComponent('taxonomy_forums');
+
+    // Assert field order is body » taxonomy » comments.
+    $this->assertTrue($taxonomy['weight'] < $body['weight']);
+    $this->assertTrue($body['weight'] < $comment['weight']);
+
+    // Check form order.
+    $display = EntityFormDisplay::load('node.forum.default');
+    $body = $display->getComponent('body');
+    $comment = $display->getComponent('comment_forum');
+    $taxonomy = $display->getComponent('taxonomy_forums');
+
+    // Assert category comes before body in order.
+    $this->assertTrue($taxonomy['weight'] < $body['weight']);
+
+    $this->generateForumTopics();
+
+    // Log in an unprivileged user to view the forum topics and generate an
+    // active forum topics list.
+    $this->drupalLogin($this->webUser);
+    // Verify that this user is shown a message that they may not post content.
+    $this->drupalGet('forum/' . $this->forum['tid']);
+    $this->assertText(t('You are not allowed to post new content in the forum'), "Authenticated user without permission to post forum content is shown message in local tasks to that effect.");
+
+    // Log in, and do basic tests for a user with permission to edit any forum
+    // content.
+    $this->doBasicTests($this->editAnyTopicsUser, TRUE);
+    // Create a forum node authored by this user.
+    $any_topics_user_node = $this->createForumTopic($this->forum, FALSE);
+
+    // Log in, and do basic tests for a user with permission to edit only its
+    // own forum content.
+    $this->doBasicTests($this->editOwnTopicsUser, FALSE);
+    // Create a forum node authored by this user.
+    $own_topics_user_node = $this->createForumTopic($this->forum, FALSE);
+    // Verify that this user cannot edit forum content authored by another user.
+    $this->verifyForums($any_topics_user_node, FALSE, 403);
+
+    // Verify that this user is shown a local task to add new forum content.
+    $this->drupalGet('forum');
+    $this->assertLink(t('Add new Forum topic'));
+    $this->drupalGet('forum/' . $this->forum['tid']);
+    $this->assertLink(t('Add new Forum topic'));
+
+    // Log in a user with permission to edit any forum content.
+    $this->drupalLogin($this->editAnyTopicsUser);
+    // Verify that this user can edit forum content authored by another user.
+    $this->verifyForums($own_topics_user_node, TRUE);
+
+    // Verify the topic and post counts on the forum page.
+    $this->drupalGet('forum');
+
+    // Verify row for testing forum.
+    $forum_arg = array(':forum' => 'forum-list-' . $this->forum['tid']);
+
+    // Topics cell contains number of topics and number of unread topics.
+    $xpath = $this->buildXPathQuery('//tr[@id=:forum]//td[@class="forum__topics"]', $forum_arg);
+    $topics = $this->xpath($xpath);
+    $topics = trim($topics[0]);
+    $this->assertEqual($topics, '6', 'Number of topics found.');
+
+    // Verify the number of unread topics.
+    $unread_topics = $this->container->get('forum_manager')->unreadTopics($this->forum['tid'], $this->editAnyTopicsUser->id());
+    $unread_topics = \Drupal::translation()->formatPlural($unread_topics, '1 new post', '@count new posts');
+    $xpath = $this->buildXPathQuery('//tr[@id=:forum]//td[@class="forum__topics"]//a', $forum_arg);
+    $this->assertFieldByXPath($xpath, $unread_topics, 'Number of unread topics found.');
+    // Verify that the forum name is in the unread topics text.
+    $xpath = $this->buildXPathQuery('//tr[@id=:forum]//em[@class="placeholder"]', $forum_arg);
+    $this->assertFieldByXpath($xpath, $this->forum['name'], 'Forum name found in unread topics text.');
+
+    // Verify total number of posts in forum.
+    $xpath = $this->buildXPathQuery('//tr[@id=:forum]//td[@class="forum__posts"]', $forum_arg);
+    $this->assertFieldByXPath($xpath, '6', 'Number of posts found.');
+
+    // Test loading multiple forum nodes on the front page.
+    $this->drupalLogin($this->drupalCreateUser(array('administer content types', 'create forum content', 'post comments')));
+    $this->drupalPostForm('admin/structure/types/manage/forum', array('options[promote]' => 'promote'), t('Save content type'));
+    $this->createForumTopic($this->forum, FALSE);
+    $this->createForumTopic($this->forum, FALSE);
+    $this->drupalGet('node');
+
+    // Test adding a comment to a forum topic.
+    $node = $this->createForumTopic($this->forum, FALSE);
+    $edit = array();
+    $edit['comment_body[0][value]'] = $this->randomMachineName();
+    $this->drupalPostForm('node/' . $node->id(), $edit, t('Save'));
+    $this->assertResponse(200);
+
+    // Test editing a forum topic that has a comment.
+    $this->drupalLogin($this->editAnyTopicsUser);
+    $this->drupalGet('forum/' . $this->forum['tid']);
+    $this->drupalPostForm('node/' . $node->id() . '/edit', array(), t('Save'));
+    $this->assertResponse(200);
+
+    // Test the root forum page title change.
+    $this->drupalGet('forum');
+    $this->assertCacheTag('config:taxonomy.vocabulary.' . $this->forum['vid']);
+    $this->assertTitle(t('Forums | Drupal'));
+    $vocabulary = Vocabulary::load($this->forum['vid']);
+    $vocabulary->set('name', 'Discussions');
+    $vocabulary->save();
+    $this->drupalGet('forum');
+    $this->assertTitle(t('Discussions | Drupal'));
+
+    // Test anonymous action link.
+    $this->drupalLogout();
+    $this->drupalGet('forum/' . $this->forum['tid']);
+    $this->assertLink(t('Log in to post new content in the forum.'));
+  }
+
+  /**
+   * Tests that forum nodes can't be added without a parent.
+   *
+   * Verifies that forum nodes are not created without choosing "forum" from the
+   * select list.
+   */
+  function testAddOrphanTopic() {
+    // Must remove forum topics to test creating orphan topics.
+    $vid = $this->config('forum.settings')->get('vocabulary');
+    $tids = \Drupal::entityQuery('taxonomy_term')
+      ->condition('vid', $vid)
+      ->execute();
+    entity_delete_multiple('taxonomy_term', $tids);
+
+    // Create an orphan forum item.
+    $edit = array();
+    $edit['title[0][value]'] = $this->randomMachineName(10);
+    $edit['body[0][value]'] = $this->randomMachineName(120);
+    $this->drupalLogin($this->adminUser);
+    $this->drupalPostForm('node/add/forum', $edit, t('Save'));
+
+    $nid_count = db_query('SELECT COUNT(nid) FROM {node}')->fetchField();
+    $this->assertEqual(0, $nid_count, 'A forum node was not created when missing a forum vocabulary.');
+
+    // Reset the defaults for future tests.
+    \Drupal::service('module_installer')->install(array('forum'));
+  }
+
+  /**
+   * Runs admin tests on the admin user.
+   *
+   * @param object $user
+   *   The logged-in user.
+   */
+  private function doAdminTests($user) {
+    // Log in the user.
+    $this->drupalLogin($user);
+
+    // Add forum to the Tools menu.
+    $edit = array();
+    $this->drupalPostForm('admin/structure/menu/manage/tools', $edit, t('Save'));
+    $this->assertResponse(200);
+
+    // Edit forum taxonomy.
+    // Restoration of the settings fails and causes subsequent tests to fail.
+    $this->editForumVocabulary();
+    // Create forum container.
+    $this->forumContainer = $this->createForum('container');
+    // Verify "edit container" link exists and functions correctly.
+    $this->drupalGet('admin/structure/forum');
+    // Verify help text is shown.
+    $this->assertText(t('Forums contain forum topics. Use containers to group related forums'));
+    // Verify action links are there.
+    $this->assertLink('Add forum');
+    $this->assertLink('Add container');
+    $this->clickLink('edit container');
+    $this->assertRaw('Edit container', 'Followed the link to edit the container');
+    // Create forum inside the forum container.
+    $this->forum = $this->createForum('forum', $this->forumContainer['tid']);
+    // Verify the "edit forum" link exists and functions correctly.
+    $this->drupalGet('admin/structure/forum');
+    $this->clickLink('edit forum');
+    $this->assertRaw('Edit forum', 'Followed the link to edit the forum');
+    // Navigate back to forum structure page.
+    $this->drupalGet('admin/structure/forum');
+    // Create second forum in container, destined to be deleted below.
+    $delete_forum = $this->createForum('forum', $this->forumContainer['tid']);
+    // Save forum overview.
+    $this->drupalPostForm('admin/structure/forum/', array(), t('Save'));
+    $this->assertRaw(t('The configuration options have been saved.'));
+    // Delete this second forum.
+    $this->deleteForum($delete_forum['tid']);
+    // Create forum at the top (root) level.
+    $this->rootForum = $this->createForum('forum');
+
+    // Test vocabulary form alterations.
+    $this->drupalGet('admin/structure/taxonomy/manage/forums');
+    $this->assertFieldByName('op', t('Save'), 'Save button found.');
+    $this->assertNoFieldByName('op', t('Delete'), 'Delete button not found.');
+
+    // Test term edit form alterations.
+    $this->drupalGet('taxonomy/term/' . $this->forumContainer['tid'] . '/edit');
+    // Test parent field been hidden by forum module.
+    $this->assertNoField('parent[]', 'Parent field not found.');
+
+    // Create a default vocabulary named "Tags".
+    $description = 'Use tags to group articles on similar topics into categories.';
+    $help = 'Enter a comma-separated list of words to describe your content.';
+    $vocabulary = Vocabulary::create([
+      'name' => 'Tags',
+      'description' => $description,
+      'vid' => 'tags',
+      'langcode' => \Drupal::languageManager()->getDefaultLanguage()->getId(),
+      'help' => $help,
+    ]);
+    $vocabulary->save();
+    // Test tags vocabulary form is not affected.
+    $this->drupalGet('admin/structure/taxonomy/manage/tags');
+    $this->assertFieldByName('op', t('Save'), 'Save button found.');
+    $this->assertLink(t('Delete'));
+    // Test tags vocabulary term form is not affected.
+    $this->drupalGet('admin/structure/taxonomy/manage/tags/add');
+    $this->assertField('parent[]', 'Parent field found.');
+    // Test relations widget exists.
+    $relations_widget = $this->xpath("//details[@id='edit-relations']");
+    $this->assertTrue(isset($relations_widget[0]), 'Relations widget element found.');
+  }
+
+  /**
+   * Edits the forum taxonomy.
+   */
+  function editForumVocabulary() {
+    // Backup forum taxonomy.
+    $vid = $this->config('forum.settings')->get('vocabulary');
+    $original_vocabulary = Vocabulary::load($vid);
+
+    // Generate a random name and description.
+    $edit = array(
+      'name' => $this->randomMachineName(10),
+      'description' => $this->randomMachineName(100),
+    );
+
+    // Edit the vocabulary.
+    $this->drupalPostForm('admin/structure/taxonomy/manage/' . $original_vocabulary->id(), $edit, t('Save'));
+    $this->assertResponse(200);
+    $this->assertRaw(t('Updated vocabulary %name.', array('%name' => $edit['name'])), 'Vocabulary was edited');
+
+    // Grab the newly edited vocabulary.
+    $current_vocabulary = Vocabulary::load($vid);
+
+    // Make sure we actually edited the vocabulary properly.
+    $this->assertEqual($current_vocabulary->label(), $edit['name'], 'The name was updated');
+    $this->assertEqual($current_vocabulary->getDescription(), $edit['description'], 'The description was updated');
+
+    // Restore the original vocabulary's name and description.
+    $current_vocabulary->set('name', $original_vocabulary->label());
+    $current_vocabulary->set('description', $original_vocabulary->getDescription());
+    $current_vocabulary->save();
+    // Reload vocabulary to make sure changes are saved.
+    $current_vocabulary = Vocabulary::load($vid);
+    $this->assertEqual($current_vocabulary->label(), $original_vocabulary->label(), 'The original vocabulary settings were restored');
+  }
+
+  /**
+   * Creates a forum container or a forum.
+   *
+   * @param string $type
+   *   The forum type (forum container or forum).
+   * @param int $parent
+   *   The forum parent. This defaults to 0, indicating a root forum.
+   *
+   * @return \Drupal\Core\Database\StatementInterface
+   *   The created taxonomy term data.
+   */
+  function createForum($type, $parent = 0) {
+    // Generate a random name/description.
+    $name = $this->randomMachineName(10);
+    $description = $this->randomMachineName(100);
+
+    $edit = array(
+      'name[0][value]' => $name,
+      'description[0][value]' => $description,
+      'parent[0]' => $parent,
+      'weight' => '0',
+    );
+
+    // Create forum.
+    $this->drupalPostForm('admin/structure/forum/add/' . $type, $edit, t('Save'));
+    $this->assertResponse(200);
+    $type = ($type == 'container') ? 'forum container' : 'forum';
+    $this->assertText(
+      t(
+        'Created new @type @term.',
+        array('@term' => $name, '@type' => t($type))
+      ),
+      format_string('@type was created', array('@type' => ucfirst($type)))
+    );
+
+    // Verify that the creation message contains a link to a term.
+    $view_link = $this->xpath('//div[@class="messages"]//a[contains(@href, :href)]', array(':href' => 'term/'));
+    $this->assert(isset($view_link), 'The message area contains a link to a term');
+
+    // Verify forum.
+    $term = db_query("SELECT * FROM {taxonomy_term_field_data} t WHERE t.vid = :vid AND t.name = :name AND t.description__value = :desc AND t.default_langcode = 1", array(':vid' => $this->config('forum.settings')->get('vocabulary'), ':name' => $name, ':desc' => $description))->fetchAssoc();
+    $this->assertTrue(!empty($term), 'The ' . $type . ' exists in the database');
+
+    // Verify forum hierarchy.
+    $tid = $term['tid'];
+    $parent_tid = db_query("SELECT t.parent FROM {taxonomy_term_hierarchy} t WHERE t.tid = :tid", array(':tid' => $tid))->fetchField();
+    $this->assertTrue($parent == $parent_tid, 'The ' . $type . ' is linked to its container');
+
+    $forum = $this->container->get('entity.manager')->getStorage('taxonomy_term')->load($tid);
+    $this->assertEqual(($type == 'forum container'), (bool) $forum->forum_container->value);
+    return $term;
+  }
+
+  /**
+   * Deletes a forum.
+   *
+   * @param int $tid
+   *   The forum ID.
+   */
+  function deleteForum($tid) {
+    // Delete the forum.
+    $this->drupalGet('admin/structure/forum/edit/forum/' . $tid);
+    $this->clickLink(t('Delete'));
+    $this->assertText('Are you sure you want to delete the forum');
+    $this->assertNoText('Add forum');
+    $this->assertNoText('Add forum container');
+    $this->drupalPostForm(NULL, array(), t('Delete'));
+
+    // Assert that the forum no longer exists.
+    $this->drupalGet('forum/' . $tid);
+    $this->assertResponse(404, 'The forum was not found');
+  }
+
+  /**
+   * Runs basic tests on the indicated user.
+   *
+   * @param \Drupal\Core\Session\AccountInterface $user
+   *   The logged in user.
+   * @param bool $admin
+   *   User has 'access administration pages' privilege.
+   */
+  private function doBasicTests($user, $admin) {
+    // Log in the user.
+    $this->drupalLogin($user);
+    // Attempt to create forum topic under a container.
+    $this->createForumTopic($this->forumContainer, TRUE);
+    // Create forum node.
+    $node = $this->createForumTopic($this->forum, FALSE);
+    // Verify the user has access to all the forum nodes.
+    $this->verifyForums($node, $admin);
+  }
+
+  /**
+   * Tests a forum with a new post displays properly.
+   */
+  function testForumWithNewPost() {
+    // Log in as the first user.
+    $this->drupalLogin($this->adminUser);
+    // Create a forum container.
+    $this->forumContainer = $this->createForum('container');
+    // Create a forum.
+    $this->forum = $this->createForum('forum');
+    // Create a topic.
+    $node = $this->createForumTopic($this->forum, FALSE);
+
+    // Log in as a second user.
+    $this->drupalLogin($this->postCommentUser);
+    // Post a reply to the topic.
+    $edit = array();
+    $edit['subject[0][value]'] = $this->randomMachineName();
+    $edit['comment_body[0][value]'] = $this->randomMachineName();
+    $this->drupalPostForm('node/' . $node->id(), $edit, t('Save'));
+    $this->assertResponse(200);
+
+    // Test replying to a comment.
+    $this->clickLink('Reply');
+    $this->assertResponse(200);
+    $this->assertFieldByName('comment_body[0][value]');
+
+    // Log in as the first user.
+    $this->drupalLogin($this->adminUser);
+    // Check that forum renders properly.
+    $this->drupalGet("forum/{$this->forum['tid']}");
+    $this->assertResponse(200);
+
+    // Verify there is no unintentional HTML tag escaping.
+    $this->assertNoEscaped('<', '');
+  }
+
+  /**
+   * Creates a forum topic.
+   *
+   * @param array $forum
+   *   A forum array.
+   * @param bool $container
+   *   TRUE if $forum is a container; FALSE otherwise.
+   *
+   * @return object
+   *   The created topic node.
+   */
+  function createForumTopic($forum, $container = FALSE) {
+    // Generate a random subject/body.
+    $title = $this->randomMachineName(20);
+    $body = $this->randomMachineName(200);
+
+    $edit = array(
+      'title[0][value]' => $title,
+      'body[0][value]' => $body,
+    );
+    $tid = $forum['tid'];
+
+    // Create the forum topic, preselecting the forum ID via a URL parameter.
+    $this->drupalPostForm('node/add/forum', $edit, t('Save'), array('query' => array('forum_id' => $tid)));
+
+    $type = t('Forum topic');
+    if ($container) {
+      $this->assertNoText(t('@type @title has been created.', array('@type' => $type, '@title' => $title)), 'Forum topic was not created');
+      $this->assertRaw(t('The item %title is a forum container, not a forum.', array('%title' => $forum['name'])), 'Error message was shown');
+      return;
+    }
+    else {
+      $this->assertText(t('@type @title has been created.', array('@type' => $type, '@title' => $title)), 'Forum topic was created');
+      $this->assertNoRaw(t('The item %title is a forum container, not a forum.', array('%title' => $forum['name'])), 'No error message was shown');
+
+      // Verify that the creation message contains a link to a term.
+      $view_link = $this->xpath('//div[@class="messages"]//a[contains(@href, :href)]', array(':href' => 'term/'));
+      $this->assert(isset($view_link), 'The message area contains a link to a term');
+    }
+
+    // Retrieve node object, ensure that the topic was created and in the proper forum.
+    $node = $this->drupalGetNodeByTitle($title);
+    $this->assertTrue($node != NULL, format_string('Node @title was loaded', array('@title' => $title)));
+    $this->assertEqual($node->taxonomy_forums->target_id, $tid, 'Saved forum topic was in the expected forum');
+
+    // View forum topic.
+    $this->drupalGet('node/' . $node->id());
+    $this->assertRaw($title, 'Subject was found');
+    $this->assertRaw($body, 'Body was found');
+
+    return $node;
+  }
+
+  /**
+   * Verifies that the logged in user has access to a forum node.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $node
+   *   The node being checked.
+   * @param bool $admin
+   *   Boolean to indicate whether the user can 'access administration pages'.
+   * @param int $response
+   *   The expected HTTP response code.
+   */
+  private function verifyForums(EntityInterface $node, $admin, $response = 200) {
+    $response2 = ($admin) ? 200 : 403;
+
+    // View forum help node.
+    $this->drupalGet('admin/help/forum');
+    $this->assertResponse($response2);
+    if ($response2 == 200) {
+      $this->assertTitle(t('Forum | Drupal'), 'Forum help title was displayed');
+      $this->assertText(t('Forum'), 'Forum help node was displayed');
+    }
+
+    // View forum container page.
+    $this->verifyForumView($this->forumContainer);
+    // View forum page.
+    $this->verifyForumView($this->forum, $this->forumContainer);
+    // View root forum page.
+    $this->verifyForumView($this->rootForum);
+
+    // View forum node.
+    $this->drupalGet('node/' . $node->id());
+    $this->assertResponse(200);
+    $this->assertTitle($node->label() . ' | Drupal', 'Forum node was displayed');
+    $breadcrumb_build = array(
+      Link::createFromRoute(t('Home'), '<front>'),
+      Link::createFromRoute(t('Forums'), 'forum.index'),
+      Link::createFromRoute($this->forumContainer['name'], 'forum.page', array('taxonomy_term' => $this->forumContainer['tid'])),
+      Link::createFromRoute($this->forum['name'], 'forum.page', array('taxonomy_term' => $this->forum['tid'])),
+    );
+    $breadcrumb = array(
+      '#theme' => 'breadcrumb',
+      '#links' => $breadcrumb_build,
+    );
+    $this->assertRaw(\Drupal::service('renderer')->renderRoot($breadcrumb), 'Breadcrumbs were displayed');
+
+    // View forum edit node.
+    $this->drupalGet('node/' . $node->id() . '/edit');
+    $this->assertResponse($response);
+    if ($response == 200) {
+      $this->assertTitle('Edit Forum topic ' . $node->label() . ' | Drupal', 'Forum edit node was displayed');
+    }
+
+    if ($response == 200) {
+      // Edit forum node (including moving it to another forum).
+      $edit = array();
+      $edit['title[0][value]'] = 'node/' . $node->id();
+      $edit['body[0][value]'] = $this->randomMachineName(256);
+      // Assume the topic is initially associated with $forum.
+      $edit['taxonomy_forums'] = $this->rootForum['tid'];
+      $edit['shadow'] = TRUE;
+      $this->drupalPostForm('node/' . $node->id() . '/edit', $edit, t('Save'));
+      $this->assertText(t('Forum topic @title has been updated.', array('@title' => $edit['title[0][value]'])), 'Forum node was edited');
+
+      // Verify topic was moved to a different forum.
+      $forum_tid = db_query("SELECT tid FROM {forum} WHERE nid = :nid AND vid = :vid", array(
+        ':nid' => $node->id(),
+        ':vid' => $node->getRevisionId(),
+      ))->fetchField();
+      $this->assertTrue($forum_tid == $this->rootForum['tid'], 'The forum topic is linked to a different forum');
+
+      // Delete forum node.
+      $this->drupalPostForm('node/' . $node->id() . '/delete', array(), t('Delete'));
+      $this->assertResponse($response);
+      $this->assertRaw(t('Forum topic %title has been deleted.', array('%title' => $edit['title[0][value]'])), 'Forum node was deleted');
+    }
+  }
+
+  /**
+   * Verifies the display of a forum page.
+   *
+   * @param array $forum
+   *   A row from the taxonomy_term_data table in an array.
+   * @param array $parent
+   *   (optional) An array representing the forum's parent.
+   */
+  private function verifyForumView($forum, $parent = NULL) {
+    // View forum page.
+    $this->drupalGet('forum/' . $forum['tid']);
+    $this->assertResponse(200);
+    $this->assertTitle($forum['name'] . ' | Drupal');
+
+    $breadcrumb_build = array(
+      Link::createFromRoute(t('Home'), '<front>'),
+      Link::createFromRoute(t('Forums'), 'forum.index'),
+    );
+    if (isset($parent)) {
+      $breadcrumb_build[] = Link::createFromRoute($parent['name'], 'forum.page', array('taxonomy_term' => $parent['tid']));
+    }
+
+    $breadcrumb = array(
+      '#theme' => 'breadcrumb',
+      '#links' => $breadcrumb_build,
+    );
+    $this->assertRaw(\Drupal::service('renderer')->renderRoot($breadcrumb), 'Breadcrumbs were displayed');
+  }
+
+  /**
+   * Generates forum topics.
+   */
+  private function generateForumTopics() {
+    $this->nids = array();
+    for ($i = 0; $i < 5; $i++) {
+      $node = $this->createForumTopic($this->forum, FALSE);
+      $this->nids[] = $node->id();
+    }
+  }
+
+}

web/core/modules/forum/src/Tests/ForumUninstallTest.php

@@ -0,0 +1,150 @@
+<?php
+
+namespace Drupal\forum\Tests;
+
+use Drupal\comment\CommentInterface;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\node\Entity\NodeType;
+use Drupal\simpletest\WebTestBase;
+use Drupal\comment\Entity\Comment;
+use Drupal\taxonomy\Entity\Term;
+
+/**
+ * Tests forum module uninstallation.
+ *
+ * @group forum
+ */
+class ForumUninstallTest extends WebTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('forum');
+
+  /**
+   * Tests if forum module uninstallation properly deletes the field.
+   */
+  public function testForumUninstallWithField() {
+    $this->drupalLogin($this->drupalCreateUser(['administer taxonomy', 'administer nodes', 'administer modules', 'delete any forum content', 'administer content types']));
+    // Ensure that the field exists before uninstallation.
+    $field_storage = FieldStorageConfig::loadByName('node', 'taxonomy_forums');
+    $this->assertNotNull($field_storage, 'The taxonomy_forums field storage exists.');
+
+    // Create a taxonomy term.
+    $term = Term::create([
+      'name' => t('A term'),
+      'langcode' => \Drupal::languageManager()->getDefaultLanguage()->getId(),
+      'description' => '',
+      'parent' => array(0),
+      'vid' => 'forums',
+      'forum_container' => 0,
+    ]);
+    $term->save();
+
+    // Create a forum node.
+    $node = $this->drupalCreateNode(array(
+      'title' => 'A forum post',
+      'type' => 'forum',
+      'taxonomy_forums' => array(array('target_id' => $term->id())),
+    ));
+
+    // Create at least one comment against the forum node.
+    $comment = Comment::create(array(
+      'entity_id' => $node->nid->value,
+      'entity_type' => 'node',
+      'field_name' => 'comment_forum',
+      'pid' => 0,
+      'uid' => 0,
+      'status' => CommentInterface::PUBLISHED,
+      'subject' => $this->randomMachineName(),
+      'hostname' => '127.0.0.1',
+    ));
+    $comment->save();
+
+    // Attempt to uninstall forum.
+    $this->drupalGet('admin/modules/uninstall');
+    // Assert forum is required.
+    $this->assertNoFieldByName('uninstall[forum]');
+    $this->assertText('To uninstall Forum, first delete all Forum content');
+
+    // Delete the node.
+    $this->drupalPostForm('node/' . $node->id() . '/delete', array(), t('Delete'));
+
+    // Attempt to uninstall forum.
+    $this->drupalGet('admin/modules/uninstall');
+    // Assert forum is still required.
+    $this->assertNoFieldByName('uninstall[forum]');
+    $this->assertText('To uninstall Forum, first delete all Forums terms');
+
+    // Delete any forum terms.
+    $vid = $this->config('forum.settings')->get('vocabulary');
+    $terms = entity_load_multiple_by_properties('taxonomy_term', ['vid' => $vid]);
+    foreach ($terms as $term) {
+      $term->delete();
+    }
+
+    // Ensure that the forum node type can not be deleted.
+    $this->drupalGet('admin/structure/types/manage/forum');
+    $this->assertNoLink(t('Delete'));
+
+    // Now attempt to uninstall forum.
+    $this->drupalGet('admin/modules/uninstall');
+    // Assert forum is no longer required.
+    $this->assertFieldByName('uninstall[forum]');
+    $this->drupalPostForm('admin/modules/uninstall', array(
+      'uninstall[forum]' => 1,
+    ), t('Uninstall'));
+    $this->drupalPostForm(NULL, [], t('Uninstall'));
+
+    // Check that the field is now deleted.
+    $field_storage = FieldStorageConfig::loadByName('node', 'taxonomy_forums');
+    $this->assertNull($field_storage, 'The taxonomy_forums field storage has been deleted.');
+
+    // Check that a node type with a machine name of forum can be created after
+    // uninstalling the forum module and the node type is not locked.
+    $edit = array(
+      'name' => 'Forum',
+      'title_label' => 'title for forum',
+      'type' => 'forum',
+    );
+    $this->drupalPostForm('admin/structure/types/add', $edit, t('Save content type'));
+    $this->assertTrue((bool) NodeType::load('forum'), 'Node type with machine forum created.');
+    $this->drupalGet('admin/structure/types/manage/forum');
+    $this->clickLink(t('Delete'));
+    $this->drupalPostForm(NULL, array(), t('Delete'));
+    $this->assertResponse(200);
+    $this->assertFalse((bool) NodeType::load('forum'), 'Node type with machine forum deleted.');
+
+    // Double check everything by reinstalling the forum module again.
+    $this->drupalPostForm('admin/modules', ['modules[Core][forum][enable]' => 1], 'Install');
+    $this->assertText('Module Forum has been enabled.');
+  }
+
+  /**
+   * Tests uninstallation if the field storage has been deleted beforehand.
+   */
+  public function testForumUninstallWithoutFieldStorage() {
+    // Manually delete the taxonomy_forums field before module uninstallation.
+    $field_storage = FieldStorageConfig::loadByName('node', 'taxonomy_forums');
+    $this->assertNotNull($field_storage, 'The taxonomy_forums field storage exists.');
+    $field_storage->delete();
+
+    // Check that the field is now deleted.
+    $field_storage = FieldStorageConfig::loadByName('node', 'taxonomy_forums');
+    $this->assertNull($field_storage, 'The taxonomy_forums field storage has been deleted.');
+
+    // Delete all terms in the Forums vocabulary. Uninstalling the forum module
+    // will fail unless this is done.
+    $terms = entity_load_multiple_by_properties('taxonomy_term', array('vid' => 'forums'));
+    foreach ($terms as $term) {
+      $term->delete();
+    }
+
+    // Ensure that uninstallation succeeds even if the field has already been
+    // deleted manually beforehand.
+    $this->container->get('module_installer')->uninstall(array('forum'));
+  }
+
+}

web/core/modules/forum/src/Tests/Views/ForumIntegrationTest.php

@@ -0,0 +1,94 @@
+<?php
+
+namespace Drupal\forum\Tests\Views;
+
+use Drupal\views\Views;
+use Drupal\views\Tests\ViewTestBase;
+use Drupal\views\Tests\ViewTestData;
+
+/**
+ * Tests the forum integration into views.
+ *
+ * @group forum
+ */
+class ForumIntegrationTest extends ViewTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('forum_test_views');
+
+  /**
+   * Views used by this test.
+   *
+   * @var array
+   */
+  public static $testViews = array('test_forum_index');
+
+  protected function setUp() {
+    parent::setUp();
+
+    ViewTestData::createTestViews(get_class($this), array('forum_test_views'));
+  }
+
+
+  /**
+   * Tests the integration.
+   */
+  public function testForumIntegration() {
+    // Create a forum.
+    $entity_manager = $this->container->get('entity.manager');
+    $term = $entity_manager->getStorage('taxonomy_term')->create(array('vid' => 'forums', 'name' => $this->randomMachineName()));
+    $term->save();
+
+    $comment_storage = $entity_manager->getStorage('comment');
+
+    // Create some nodes which are part of this forum with some comments.
+    $nodes = array();
+    for ($i = 0; $i < 3; $i++) {
+      $node = $this->drupalCreateNode(array('type' => 'forum', 'taxonomy_forums' => array($term->id()), 'sticky' => $i == 0 ? NODE_STICKY : NODE_NOT_STICKY));
+      $nodes[] = $node;
+    }
+
+    $account = $this->drupalCreateUser(array('skip comment approval'));
+    $this->drupalLogin($account);
+
+    $comments = array();
+    foreach ($nodes as $index => $node) {
+      for ($i = 0; $i <= $index; $i++) {
+        $comment = $comment_storage->create(array('entity_type' => 'node', 'entity_id' => $node->id(), 'field_name' => 'comment_forum'));
+        $comment->save();
+        $comments[$comment->get('entity_id')->target_id][$comment->id()] = $comment;
+      }
+    }
+
+    $view = Views::getView('test_forum_index');
+    $this->executeView($view);
+
+    $expected_result = array();
+    $expected_result[] = array(
+      'nid' => $nodes[0]->id(),
+      'sticky' => NODE_STICKY,
+      'comment_count' => 1.
+    );
+    $expected_result[] = array(
+      'nid' => $nodes[1]->id(),
+      'sticky' => NODE_NOT_STICKY,
+      'comment_count' => 2.
+    );
+    $expected_result[] = array(
+      'nid' => $nodes[2]->id(),
+      'sticky' => NODE_NOT_STICKY,
+      'comment_count' => 3.
+    );
+    $column_map = array(
+      'nid' => 'nid',
+      'forum_index_sticky' => 'sticky',
+      'forum_index_comment_count' => 'comment_count',
+    );
+    $this->assertIdenticalResultset($view, $expected_result, $column_map);
+  }
+
+}

web/core/modules/forum/templates/forum-icon.html.twig

@@ -0,0 +1,26 @@
+{#
+/**
+ * @file
+ * Default theme implementation to display a status icon for a forum post.
+ *
+ * Available variables:
+ * - attributes: HTML attributes to be applied to the wrapper element.
+ *   - class: HTML classes that determine which icon to display. May be one of
+ *     'hot', 'hot-new', 'new', 'default', 'closed', or 'sticky'.
+ *   - title: Text alternative for the forum icon.
+ * - icon_title: Text alternative for the forum icon, same as above.
+ * - new_posts: '1' when this topic contains new posts, otherwise '0'.
+ * - first_new: '1' when this is the first topic with new posts, otherwise '0'.
+ * - icon_status: Indicates which status icon should be used.
+ *
+ * @see template_preprocess_forum_icon()
+ *
+ * @ingroup themeable
+ */
+#}
+<div{{ attributes }}>
+  {% if first_new -%}
+    <a id="new"></a>
+  {%- endif %}
+  <span class="visually-hidden">{{ icon_title }}</span>
+</div>

web/core/modules/forum/templates/forum-list.html.twig

@@ -0,0 +1,77 @@
+{#
+/**
+ * @file
+ * Default theme implementation to display a list of forums and containers.
+ *
+ * Available variables:
+ * - forums: A collection of forums and containers to display. It is keyed to
+ *   the numeric IDs of all child forums and containers. Each forum in forums
+ *   contains:
+ *   - is_container: A flag indicating if the forum can contain other
+ *     forums. Otherwise, the forum can only contain topics.
+ *   - depth: How deep the forum is in the current hierarchy.
+ *   - zebra: 'even' or 'odd', used for row class.
+ *   - icon_class: 'default' or 'new', used for forum icon class.
+ *   - icon_title: Text alternative for the forum icon.
+ *   - name: The name of the forum.
+ *   - link: The URL to link to this forum.
+ *   - description: The description field for the forum, containing:
+ *     - value: The descriptive text for the forum.
+ *   - new_topics: A flag indicating if the forum contains unread posts.
+ *   - new_url: A URL to the forum's unread posts.
+ *   - new_text: Text for the above URL, which tells how many new posts.
+ *   - old_topics: A count of posts that have already been read.
+ *   - num_posts: The total number of posts in the forum.
+ *   - last_reply: Text representing the last time a forum was posted or
+ *     commented in.
+ * - forum_id: Forum ID for the current forum. Parent to all items within the
+ *   forums array.
+ *
+ * @see template_preprocess_forum_list()
+ *
+ * @ingroup themeable
+ */
+#}
+<table>
+  <thead>
+    <tr>
+      <th>{{ 'Forum'|t }}</th>
+      <th>{{ 'Topics'|t }}</th>
+      <th>{{ 'Posts'|t }}</th>
+      <th>{{ 'Last post'|t }}</th>
+    </tr>
+  </thead>
+  <tbody>
+  {% for child_id, forum in forums %}
+    <tr>
+      <td{% if forum.is_container == true %} colspan="4"{% endif %}>
+        {#
+          Enclose the contents of this cell with X divs, where X is the
+          depth this forum resides at. This will allow us to use CSS
+          left-margin for indenting.
+        #}
+        {% for i in 1..forum.depth if forum.depth > 0 %}<div class="indent">{% endfor %}
+          <div title="{{ forum.icon_title }}">
+            <span class="visually-hidden">{{ forum.icon_title }}</span>
+          </div>
+          <div><a href="{{ forum.link }}">{{ forum.label }}</a></div>
+          {% if forum.description.value %}
+            <div>{{ forum.description.value }}</div>
+          {% endif %}
+        {% for i in 1..forum.depth if forum.depth > 0 %}</div>{% endfor %}
+      </td>
+      {% if forum.is_container == false %}
+        <td>
+          {{ forum.num_topics }}
+          {% if forum.new_topics == true %}
+            <br />
+            <a href="{{ forum.new_url }}">{{ forum.new_text }}</a>
+          {% endif %}
+        </td>
+        <td>{{ forum.num_posts }}</td>
+        <td>{{ forum.last_reply }}</td>
+      {% endif %}
+    </tr>
+  {% endfor %}
+  </tbody>
+</table>

web/core/modules/forum/templates/forum-submitted.html.twig

@@ -0,0 +1,23 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a forum post submission string.
+ *
+ * The submission string indicates when and by whom a topic was submitted.
+ *
+ * Available variables:
+ * - author: The author of the post.
+ * - time: How long ago the post was created.
+ * - topic: An object with the raw data of the post. Potentially unsafe. Be
+ *   sure to clean this data before printing.
+ *
+ * @see template_preprocess_forum_submitted()
+ *
+ * @ingroup themeable
+ */
+#}
+{% if time %}
+  <span>{% trans %}By {{ author }} {{ time }} ago{% endtrans %}</span>
+{% else %}
+  {{ 'n/a'|t }}
+{% endif %}

web/core/modules/forum/templates/forums.html.twig

@@ -0,0 +1,23 @@
+{#
+/**
+ * @file
+ * Default theme implementation to display a forum.
+ *
+ * May contain forum containers as well as forum topics.
+ *
+ * Available variables:
+ * - forums: The forums to display (as processed by forum-list.html.twig).
+ * - topics: The topics to display.
+ * - topics_pager: The topics pager.
+ * - forums_defined: A flag to indicate that the forums are configured.
+ *
+ * @see template_preprocess_forums()
+ *
+ * @ingroup themeable
+ */
+#}
+{% if forums_defined %}
+  {{ forums }}
+  {{ topics }}
+  {{ topics_pager }}
+{% endif %}

web/core/modules/forum/tests/modules/forum_test_views/forum_test_views.info.yml

@@ -0,0 +1,9 @@
+name: 'Forum test views'
+type: module
+description: 'Provides default views for views forum tests.'
+package: Testing
+version: VERSION
+core: 8.x
+dependencies:
+  - forum
+  - views

web/core/modules/forum/tests/modules/forum_test_views/test_views/views.view.test_forum_index.yml

@@ -0,0 +1,149 @@
+langcode: en
+status: true
+dependencies: {  }
+id: test_forum_index
+label: test_forum_index
+module: views
+description: ''
+tag: ''
+base_table: forum_index
+base_field: nid
+core: 8.x
+display:
+  default:
+    display_plugin: default
+    id: default
+    display_title: Master
+    position: null
+    display_options:
+      access:
+        type: none
+      cache:
+        type: tag
+      query:
+        type: views_query
+      exposed_form:
+        type: basic
+      pager:
+        type: full
+      style:
+        type: default
+      row:
+        type: fields
+      fields:
+        nid:
+          table: forum_index
+          field: nid
+          id: nid
+        sticky:
+          id: sticky
+          table: forum_index
+          field: sticky
+          relationship: none
+          group_type: group
+          admin_label: ''
+          label: Sticky
+          exclude: false
+          alter:
+            alter_text: false
+            text: ''
+            make_link: false
+            path: ''
+            absolute: false
+            external: false
+            replace_spaces: false
+            path_case: none
+            trim_whitespace: false
+            alt: ''
+            rel: ''
+            link_class: ''
+            prefix: ''
+            suffix: ''
+            target: ''
+            nl2br: false
+            max_length: 0
+            word_boundary: true
+            ellipsis: true
+            more_link: false
+            more_link_text: ''
+            more_link_path: ''
+            strip_tags: false
+            trim: false
+            preserve_tags: ''
+            html: false
+          element_type: ''
+          element_class: ''
+          element_label_type: ''
+          element_label_class: ''
+          element_label_colon: true
+          element_wrapper_type: ''
+          element_wrapper_class: ''
+          element_default_classes: true
+          empty: ''
+          hide_empty: false
+          empty_zero: false
+          hide_alter_empty: true
+          type: yes-no
+          type_custom_true: ''
+          type_custom_false: ''
+          not: false
+          plugin_id: boolean
+        comment_count:
+          id: comment_count
+          table: forum_index
+          field: comment_count
+          relationship: none
+          group_type: group
+          admin_label: ''
+          label: 'Comment count'
+          exclude: false
+          alter:
+            alter_text: false
+            text: ''
+            make_link: false
+            path: ''
+            absolute: false
+            external: false
+            replace_spaces: false
+            path_case: none
+            trim_whitespace: false
+            alt: ''
+            rel: ''
+            link_class: ''
+            prefix: ''
+            suffix: ''
+            target: ''
+            nl2br: false
+            max_length: 0
+            word_boundary: true
+            ellipsis: true
+            more_link: false
+            more_link_text: ''
+            more_link_path: ''
+            strip_tags: false
+            trim: false
+            preserve_tags: ''
+            html: false
+          element_type: ''
+          element_class: ''
+          element_label_type: ''
+          element_label_class: ''
+          element_label_colon: true
+          element_wrapper_type: ''
+          element_wrapper_class: ''
+          element_default_classes: true
+          empty: ''
+          hide_empty: false
+          empty_zero: false
+          hide_alter_empty: true
+          set_precision: false
+          precision: 0
+          decimal: .
+          separator: ','
+          format_plural: false
+          format_plural_string: "1\x03@count"
+          prefix: ''
+          suffix: ''
+          plugin_id: numeric
+      filters: {  }
+      sorts: {  }

web/core/modules/forum/tests/src/Kernel/ForumValidationTest.php

@@ -0,0 +1,65 @@
+<?php
+
+namespace Drupal\Tests\forum\Kernel;
+
+use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;
+use Drupal\node\Entity\Node;
+use Drupal\taxonomy\Entity\Term;
+
+/**
+ * Tests forum validation constraints.
+ *
+ * @group forum
+ */
+class ForumValidationTest extends EntityKernelTestBase {
+
+  /**
+   * Modules to install.
+   *
+   * @var array
+   */
+  public static $modules = ['node', 'options', 'comment', 'taxonomy', 'forum'];
+
+  /**
+   * Tests the forum validation constraints.
+   */
+  public function testValidation() {
+    // Add a forum.
+    $forum = Term::create([
+      'name' => 'forum 1',
+      'vid' => 'forums',
+      'forum_container' => 0,
+    ]);
+
+    // Add a container.
+    $container = Term::create([
+      'name' => 'container 1',
+      'vid' => 'forums',
+      'forum_container' => 1,
+    ]);
+
+    // Add a forum post.
+    $forum_post = Node::create([
+      'type' => 'forum',
+      'title' => 'Do these pants make my butt look big?',
+    ]);
+
+    $violations = $forum_post->validate();
+    $this->assertEqual(count($violations), 1);
+    $this->assertEqual($violations[0]->getMessage(), 'This value should not be null.');
+
+    // Add the forum term.
+    $forum_post->set('taxonomy_forums', $forum);
+    $violations = $forum_post->validate();
+    $this->assertEqual(count($violations), 0);
+
+    // Try to use a container.
+    $forum_post->set('taxonomy_forums', $container);
+    $violations = $forum_post->validate();
+    $this->assertEqual(count($violations), 1);
+    $this->assertEqual($violations[0]->getMessage(), t('The item %forum is a forum container, not a forum. Select one of the forums below instead.', [
+      '%forum' => $container->label(),
+    ]));
+  }
+
+}

web/core/modules/forum/tests/src/Kernel/Migrate/d6/MigrateForumConfigsTest.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace Drupal\Tests\forum\Kernel\Migrate\d6;
+
+use Drupal\config\Tests\SchemaCheckTestTrait;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Upgrade variables to forum.settings.yml.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateForumConfigsTest extends MigrateDrupal6TestBase {
+
+  use SchemaCheckTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = array('comment', 'forum', 'taxonomy');
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->executeMigration('d6_taxonomy_vocabulary');
+    $this->executeMigration('d6_forum_settings');
+  }
+
+  /**
+   * Tests migration of forum variables to forum.settings.yml.
+   */
+  public function testForumSettings() {
+    $config = $this->config('forum.settings');
+    $this->assertIdentical(15, $config->get('topics.hot_threshold'));
+    $this->assertIdentical(25, $config->get('topics.page_limit'));
+    $this->assertIdentical(1, $config->get('topics.order'));
+    $this->assertIdentical('vocabulary_1_i_0_', $config->get('vocabulary'));
+    // This is 'forum_block_num_0' in D6, but block:active:limit' in D8.
+    $this->assertIdentical(5, $config->get('block.active.limit'));
+    // This is 'forum_block_num_1' in D6, but 'block:new:limit' in D8.
+    $this->assertIdentical(5, $config->get('block.new.limit'));
+    $this->assertConfigSchema(\Drupal::service('config.typed'), 'forum.settings', $config->get());
+  }
+
+}

web/core/modules/forum/tests/src/Kernel/Migrate/d7/MigrateForumSettingsTest.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace Drupal\Tests\forum\Kernel\Migrate\d7;
+
+use Drupal\Tests\migrate_drupal\Kernel\d7\MigrateDrupal7TestBase;
+
+/**
+ * Tests migration of Forum's variables to configuration.
+ *
+ * @group forum
+ */
+class MigrateForumSettingsTest extends MigrateDrupal7TestBase {
+
+  // Don't alphabetize these. They're in dependency order.
+  public static $modules = [
+    'comment',
+    'field',
+    'filter',
+    'text',
+    'node',
+    'taxonomy',
+    'forum',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->executeMigration('d7_taxonomy_vocabulary');
+    $this->executeMigration('d7_forum_settings');
+  }
+
+  /**
+   * Tests the migration of Forum's settings to configuration.
+   */
+  public function testForumSettingsMigration() {
+    $config = $this->config('forum.settings');
+    $this->assertIdentical(9, $config->get('block.active.limit'));
+    $this->assertIdentical(4, $config->get('block.new.limit'));
+    $this->assertIdentical(10, $config->get('topics.hot_threshold'));
+    $this->assertIdentical(25, $config->get('topics.page_limit'));
+    $this->assertIdentical(1, $config->get('topics.order'));
+    $this->assertIdentical('forums', $config->get('vocabulary'));
+  }
+
+}

web/core/modules/forum/tests/src/Unit/Breadcrumb/ForumBreadcrumbBuilderBaseTest.php

@@ -0,0 +1,160 @@
+<?php
+
+namespace Drupal\Tests\forum\Unit\Breadcrumb;
+
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Link;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\DependencyInjection\Container;
+
+/**
+ * @coversDefaultClass \Drupal\forum\Breadcrumb\ForumBreadcrumbBuilderBase
+ * @group forum
+ */
+class ForumBreadcrumbBuilderBaseTest extends UnitTestCase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $cache_contexts_manager = $this->getMockBuilder('Drupal\Core\Cache\Context\CacheContextsManager')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $cache_contexts_manager->method('assertValidTokens')->willReturn(TRUE);
+    $container = new Container();
+    $container->set('cache_contexts_manager', $cache_contexts_manager);
+    \Drupal::setContainer($container);
+  }
+
+  /**
+   * Tests ForumBreadcrumbBuilderBase::__construct().
+   *
+   * @covers ::__construct
+   */
+  public function testConstructor() {
+    // Make some test doubles.
+    $entity_manager = $this->getMock('Drupal\Core\Entity\EntityManagerInterface');
+    $config_factory = $this->getConfigFactoryStub(
+      array(
+        'forum.settings' => array('IAmATestKey' => 'IAmATestValue'),
+      )
+    );
+    $forum_manager = $this->getMock('Drupal\forum\ForumManagerInterface');
+    $translation_manager = $this->getMock('Drupal\Core\StringTranslation\TranslationInterface');
+
+    // Make an object to test.
+    $builder = $this->getMockForAbstractClass(
+      'Drupal\forum\Breadcrumb\ForumBreadcrumbBuilderBase',
+      // Constructor array.
+      array(
+        $entity_manager,
+        $config_factory,
+        $forum_manager,
+        $translation_manager,
+      )
+    );
+
+    // Reflect upon our properties, except for config which is a special case.
+    $property_names = array(
+      'entityManager' => $entity_manager,
+      'forumManager' => $forum_manager,
+      'stringTranslation' => $translation_manager,
+    );
+    foreach ($property_names as $property_name => $property_value) {
+      $this->assertAttributeEquals(
+        $property_value, $property_name, $builder
+      );
+    }
+
+    // Test that the constructor made a config object with our info in it.
+    $reflector = new \ReflectionClass($builder);
+    $ref_property = $reflector->getProperty('config');
+    $ref_property->setAccessible(TRUE);
+    $config = $ref_property->getValue($builder);
+    $this->assertEquals('IAmATestValue', $config->get('IAmATestKey'));
+  }
+
+  /**
+   * Tests ForumBreadcrumbBuilderBase::build().
+   *
+   * @see \Drupal\forum\Breadcrumb\ForumBreadcrumbBuilderBase::build()
+   *
+   * @covers ::build
+   */
+  public function testBuild() {
+    // Build all our dependencies, backwards.
+    $translation_manager = $this->getMockBuilder('Drupal\Core\StringTranslation\TranslationInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $forum_manager = $this->getMockBuilder('Drupal\forum\ForumManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $prophecy = $this->prophesize('Drupal\taxonomy\VocabularyInterface');
+    $prophecy->label()->willReturn('Fora_is_the_plural_of_forum');
+    $prophecy->id()->willReturn(5);
+    $prophecy->getCacheTags()->willReturn(['taxonomy_vocabulary:5']);
+    $prophecy->getCacheContexts()->willReturn([]);
+    $prophecy->getCacheMaxAge()->willReturn(Cache::PERMANENT);
+
+    $vocab_storage = $this->getMock('Drupal\Core\Entity\EntityStorageInterface');
+    $vocab_storage->expects($this->any())
+      ->method('load')
+      ->will($this->returnValueMap(array(
+        array('forums', $prophecy->reveal()),
+      )));
+
+    $entity_manager = $this->getMockBuilder('Drupal\Core\Entity\EntityManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $entity_manager->expects($this->any())
+      ->method('getStorage')
+      ->will($this->returnValueMap(array(
+        array('taxonomy_vocabulary', $vocab_storage),
+      )));
+
+    $config_factory = $this->getConfigFactoryStub(
+      array(
+        'forum.settings' => array(
+          'vocabulary' => 'forums',
+        ),
+      )
+    );
+
+    // Build a breadcrumb builder to test.
+    $breadcrumb_builder = $this->getMockForAbstractClass(
+      'Drupal\forum\Breadcrumb\ForumBreadcrumbBuilderBase',
+      // Constructor array.
+      array(
+        $entity_manager,
+        $config_factory,
+        $forum_manager,
+        $translation_manager,
+      )
+    );
+
+    // Add a translation manager for t().
+    $translation_manager = $this->getStringTranslationStub();
+    $breadcrumb_builder->setStringTranslation($translation_manager);
+
+    // Our empty data set.
+    $route_match = $this->getMock('Drupal\Core\Routing\RouteMatchInterface');
+
+    // Expected result set.
+    $expected = array(
+      Link::createFromRoute('Home', '<front>'),
+      Link::createFromRoute('Fora_is_the_plural_of_forum', 'forum.index'),
+    );
+
+    // And finally, the test.
+    $breadcrumb = $breadcrumb_builder->build($route_match);
+    $this->assertEquals($expected, $breadcrumb->getLinks());
+    $this->assertEquals(['route'], $breadcrumb->getCacheContexts());
+    $this->assertEquals(['taxonomy_vocabulary:5'], $breadcrumb->getCacheTags());
+    $this->assertEquals(Cache::PERMANENT, $breadcrumb->getCacheMaxAge());
+  }
+
+}

web/core/modules/forum/tests/src/Unit/Breadcrumb/ForumListingBreadcrumbBuilderTest.php

@@ -0,0 +1,237 @@
+<?php
+
+namespace Drupal\Tests\forum\Unit\Breadcrumb;
+
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Link;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\DependencyInjection\Container;
+
+/**
+ * @coversDefaultClass \Drupal\forum\Breadcrumb\ForumListingBreadcrumbBuilder
+ * @group forum
+ */
+class ForumListingBreadcrumbBuilderTest extends UnitTestCase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $cache_contexts_manager = $this->getMockBuilder('Drupal\Core\Cache\Context\CacheContextsManager')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $cache_contexts_manager->method('assertValidTokens')->willReturn(TRUE);
+    $container = new Container();
+    $container->set('cache_contexts_manager', $cache_contexts_manager);
+    \Drupal::setContainer($container);
+  }
+
+  /**
+   * Tests ForumListingBreadcrumbBuilder::applies().
+   *
+   * @param bool $expected
+   *   ForumListingBreadcrumbBuilder::applies() expected result.
+   * @param string|null $route_name
+   *   (optional) A route name.
+   * @param array $parameter_map
+   *   (optional) An array of parameter names and values.
+   *
+   * @dataProvider providerTestApplies
+   * @covers ::applies
+   */
+  public function testApplies($expected, $route_name = NULL, $parameter_map = array()) {
+    // Make some test doubles.
+    $entity_manager = $this->getMock('Drupal\Core\Entity\EntityManagerInterface');
+    $config_factory = $this->getConfigFactoryStub(array());
+    $forum_manager = $this->getMock('Drupal\forum\ForumManagerInterface');
+    $translation_manager = $this->getMock('Drupal\Core\StringTranslation\TranslationInterface');
+
+    // Make an object to test.
+    $builder = $this->getMockBuilder('Drupal\forum\Breadcrumb\ForumListingBreadcrumbBuilder')
+      ->setConstructorArgs(array(
+        $entity_manager,
+        $config_factory,
+        $forum_manager,
+        $translation_manager,
+      ))
+      ->setMethods(NULL)
+      ->getMock();
+
+    $route_match = $this->getMock('Drupal\Core\Routing\RouteMatchInterface');
+    $route_match->expects($this->once())
+      ->method('getRouteName')
+      ->will($this->returnValue($route_name));
+    $route_match->expects($this->any())
+      ->method('getParameter')
+      ->will($this->returnValueMap($parameter_map));
+
+    $this->assertEquals($expected, $builder->applies($route_match));
+  }
+
+  /**
+   * Provides test data for testApplies().
+   *
+   * @return array
+   *   Array of datasets for testApplies(). Structured as such:
+   *   - ForumListBreadcrumbBuilder::applies() expected result.
+   *   - ForumListBreadcrumbBuilder::applies() $attributes input array.
+   */
+  public function providerTestApplies() {
+    // Send a Node mock, because NodeInterface cannot be mocked.
+    $mock_term = $this->getMockBuilder('Drupal\taxonomy\Entity\Term')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    return array(
+      array(
+        FALSE,
+      ),
+      array(
+        FALSE,
+        'NOT.forum.page',
+      ),
+      array(
+        FALSE,
+        'forum.page',
+      ),
+      array(
+        TRUE,
+        'forum.page',
+        array(array('taxonomy_term', 'anything')),
+      ),
+      array(
+        TRUE,
+        'forum.page',
+        array(array('taxonomy_term', $mock_term)),
+      ),
+    );
+  }
+
+  /**
+   * Tests ForumListingBreadcrumbBuilder::build().
+   *
+   * @see \Drupal\forum\ForumListingBreadcrumbBuilder::build()
+   *
+   * @covers ::build
+   */
+  public function testBuild() {
+    // Build all our dependencies, backwards.
+    $translation_manager = $this->getMockBuilder('Drupal\Core\StringTranslation\TranslationInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $prophecy = $this->prophesize('Drupal\taxonomy\Entity\Term');
+    $prophecy->label()->willReturn('Something');
+    $prophecy->id()->willReturn(1);
+    $prophecy->getCacheTags()->willReturn(['taxonomy_term:1']);
+    $prophecy->getCacheContexts()->willReturn([]);
+    $prophecy->getCacheMaxAge()->willReturn(Cache::PERMANENT);
+    $term1 = $prophecy->reveal();
+
+    $prophecy = $this->prophesize('Drupal\taxonomy\Entity\Term');
+    $prophecy->label()->willReturn('Something else');
+    $prophecy->id()->willReturn(2);
+    $prophecy->getCacheTags()->willReturn(['taxonomy_term:2']);
+    $prophecy->getCacheContexts()->willReturn([]);
+    $prophecy->getCacheMaxAge()->willReturn(Cache::PERMANENT);
+    $term2 = $prophecy->reveal();
+
+    $forum_manager = $this->getMock('Drupal\forum\ForumManagerInterface');
+    $forum_manager->expects($this->at(0))
+      ->method('getParents')
+      ->will($this->returnValue(array($term1)));
+    $forum_manager->expects($this->at(1))
+      ->method('getParents')
+      ->will($this->returnValue(array($term1, $term2)));
+
+    // The root forum.
+    $prophecy = $this->prophesize('Drupal\taxonomy\VocabularyInterface');
+    $prophecy->label()->willReturn('Fora_is_the_plural_of_forum');
+    $prophecy->id()->willReturn(5);
+    $prophecy->getCacheTags()->willReturn(['taxonomy_vocabulary:5']);
+    $prophecy->getCacheContexts()->willReturn([]);
+    $prophecy->getCacheMaxAge()->willReturn(Cache::PERMANENT);
+    $vocab_storage = $this->getMock('Drupal\Core\Entity\EntityStorageInterface');
+    $vocab_storage->expects($this->any())
+      ->method('load')
+      ->will($this->returnValueMap(array(
+        array('forums', $prophecy->reveal()),
+      )));
+
+    $entity_manager = $this->getMockBuilder('Drupal\Core\Entity\EntityManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $entity_manager->expects($this->any())
+      ->method('getStorage')
+      ->will($this->returnValueMap(array(
+        array('taxonomy_vocabulary', $vocab_storage),
+      )));
+
+    $config_factory = $this->getConfigFactoryStub(
+      array(
+        'forum.settings' => array(
+          'vocabulary' => 'forums',
+        ),
+      )
+    );
+
+    // Build a breadcrumb builder to test.
+    $breadcrumb_builder = $this->getMock(
+      'Drupal\forum\Breadcrumb\ForumListingBreadcrumbBuilder', NULL, array(
+        $entity_manager,
+        $config_factory,
+        $forum_manager,
+        $translation_manager,
+      )
+    );
+
+    // Add a translation manager for t().
+    $translation_manager = $this->getStringTranslationStub();
+    $breadcrumb_builder->setStringTranslation($translation_manager);
+
+    // The forum listing we need a breadcrumb back from.
+    $prophecy = $this->prophesize('Drupal\taxonomy\Entity\Term');
+    $prophecy->label()->willReturn('You_should_not_see_this');
+    $prophecy->id()->willReturn(23);
+    $prophecy->getCacheTags()->willReturn(['taxonomy_term:23']);
+    $prophecy->getCacheContexts()->willReturn([]);
+    $prophecy->getCacheMaxAge()->willReturn(Cache::PERMANENT);
+    $forum_listing = $prophecy->reveal();
+
+    // Our data set.
+    $route_match = $this->getMock('Drupal\Core\Routing\RouteMatchInterface');
+    $route_match->expects($this->exactly(2))
+      ->method('getParameter')
+      ->with('taxonomy_term')
+      ->will($this->returnValue($forum_listing));
+
+    // First test.
+    $expected1 = array(
+      Link::createFromRoute('Home', '<front>'),
+      Link::createFromRoute('Fora_is_the_plural_of_forum', 'forum.index'),
+      Link::createFromRoute('Something', 'forum.page', array('taxonomy_term' => 1)),
+    );
+    $breadcrumb = $breadcrumb_builder->build($route_match);
+    $this->assertEquals($expected1, $breadcrumb->getLinks());
+    $this->assertEquals(['route'], $breadcrumb->getCacheContexts());
+    $this->assertEquals(['taxonomy_term:1', 'taxonomy_term:23', 'taxonomy_vocabulary:5'], $breadcrumb->getCacheTags());
+    $this->assertEquals(Cache::PERMANENT, $breadcrumb->getCacheMaxAge());
+
+    // Second test.
+    $expected2 = array(
+      Link::createFromRoute('Home', '<front>'),
+      Link::createFromRoute('Fora_is_the_plural_of_forum', 'forum.index'),
+      Link::createFromRoute('Something else', 'forum.page', array('taxonomy_term' => 2)),
+      Link::createFromRoute('Something', 'forum.page', array('taxonomy_term' => 1)),
+    );
+    $breadcrumb = $breadcrumb_builder->build($route_match);
+    $this->assertEquals($expected2, $breadcrumb->getLinks());
+    $this->assertEquals(['route'], $breadcrumb->getCacheContexts());
+    $this->assertEquals(['taxonomy_term:1', 'taxonomy_term:2', 'taxonomy_term:23', 'taxonomy_vocabulary:5'], $breadcrumb->getCacheTags());
+    $this->assertEquals(Cache::PERMANENT, $breadcrumb->getCacheMaxAge());
+
+  }
+
+}

web/core/modules/forum/tests/src/Unit/Breadcrumb/ForumNodeBreadcrumbBuilderTest.php

@@ -0,0 +1,243 @@
+<?php
+
+namespace Drupal\Tests\forum\Unit\Breadcrumb;
+
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Link;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\DependencyInjection\Container;
+
+/**
+ * @coversDefaultClass \Drupal\forum\Breadcrumb\ForumNodeBreadcrumbBuilder
+ * @group forum
+ */
+class ForumNodeBreadcrumbBuilderTest extends UnitTestCase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $cache_contexts_manager = $this->getMockBuilder('Drupal\Core\Cache\Context\CacheContextsManager')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $cache_contexts_manager->method('assertValidTokens')->willReturn(TRUE);
+    $container = new Container();
+    $container->set('cache_contexts_manager', $cache_contexts_manager);
+    \Drupal::setContainer($container);
+  }
+
+  /**
+   * Tests ForumNodeBreadcrumbBuilder::applies().
+   *
+   * @param bool $expected
+   *   ForumNodeBreadcrumbBuilder::applies() expected result.
+   * @param string|null $route_name
+   *   (optional) A route name.
+   * @param array $parameter_map
+   *   (optional) An array of parameter names and values.
+   *
+   * @dataProvider providerTestApplies
+   * @covers ::applies
+   */
+  public function testApplies($expected, $route_name = NULL, $parameter_map = array()) {
+    // Make some test doubles.
+    $entity_manager = $this->getMock('Drupal\Core\Entity\EntityManagerInterface');
+    $config_factory = $this->getConfigFactoryStub(array());
+
+    $forum_manager = $this->getMock('Drupal\forum\ForumManagerInterface');
+    $forum_manager->expects($this->any())
+      ->method('checkNodeType')
+      ->will($this->returnValue(TRUE));
+
+    $translation_manager = $this->getMock('Drupal\Core\StringTranslation\TranslationInterface');
+
+    // Make an object to test.
+    $builder = $this->getMockBuilder('Drupal\forum\Breadcrumb\ForumNodeBreadcrumbBuilder')
+      ->setConstructorArgs(
+        array(
+          $entity_manager,
+          $config_factory,
+          $forum_manager,
+          $translation_manager,
+        )
+      )
+      ->setMethods(NULL)
+      ->getMock();
+
+    $route_match = $this->getMock('Drupal\Core\Routing\RouteMatchInterface');
+    $route_match->expects($this->once())
+      ->method('getRouteName')
+      ->will($this->returnValue($route_name));
+    $route_match->expects($this->any())
+      ->method('getParameter')
+      ->will($this->returnValueMap($parameter_map));
+
+    $this->assertEquals($expected, $builder->applies($route_match));
+  }
+
+  /**
+   * Provides test data for testApplies().
+   *
+   * Note that this test is incomplete, because we can't mock NodeInterface.
+   *
+   * @return array
+   *   Array of datasets for testApplies(). Structured as such:
+   *   - ForumNodeBreadcrumbBuilder::applies() expected result.
+   *   - ForumNodeBreadcrumbBuilder::applies() $attributes input array.
+   */
+  public function providerTestApplies() {
+    // Send a Node mock, because NodeInterface cannot be mocked.
+    $mock_node = $this->getMockBuilder('Drupal\node\Entity\Node')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    return array(
+      array(
+        FALSE,
+      ),
+      array(
+        FALSE,
+        'NOT.entity.node.canonical',
+      ),
+      array(
+        FALSE,
+        'entity.node.canonical',
+      ),
+      array(
+        FALSE,
+        'entity.node.canonical',
+        array(array('node', NULL)),
+      ),
+      array(
+        TRUE,
+        'entity.node.canonical',
+        array(array('node', $mock_node)),
+      ),
+    );
+  }
+
+  /**
+   * Tests ForumNodeBreadcrumbBuilder::build().
+   *
+   * @see \Drupal\forum\ForumNodeBreadcrumbBuilder::build()
+   * @covers ::build
+   */
+  public function testBuild() {
+    // Build all our dependencies, backwards.
+    $translation_manager = $this->getMockBuilder('Drupal\Core\StringTranslation\TranslationInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $prophecy = $this->prophesize('Drupal\taxonomy\Entity\Term');
+    $prophecy->label()->willReturn('Something');
+    $prophecy->id()->willReturn(1);
+    $prophecy->getCacheTags()->willReturn(['taxonomy_term:1']);
+    $prophecy->getCacheContexts()->willReturn([]);
+    $prophecy->getCacheMaxAge()->willReturn(Cache::PERMANENT);
+    $term1 = $prophecy->reveal();
+
+    $prophecy = $this->prophesize('Drupal\taxonomy\Entity\Term');
+    $prophecy->label()->willReturn('Something else');
+    $prophecy->id()->willReturn(2);
+    $prophecy->getCacheTags()->willReturn(['taxonomy_term:2']);
+    $prophecy->getCacheContexts()->willReturn([]);
+    $prophecy->getCacheMaxAge()->willReturn(Cache::PERMANENT);
+    $term2 = $prophecy->reveal();
+
+    $forum_manager = $this->getMockBuilder('Drupal\forum\ForumManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $forum_manager->expects($this->at(0))
+      ->method('getParents')
+      ->will($this->returnValue(array($term1)));
+    $forum_manager->expects($this->at(1))
+      ->method('getParents')
+      ->will($this->returnValue(array($term1, $term2)));
+
+    $prophecy = $this->prophesize('Drupal\taxonomy\VocabularyInterface');
+    $prophecy->label()->willReturn('Forums');
+    $prophecy->id()->willReturn(5);
+    $prophecy->getCacheTags()->willReturn(['taxonomy_vocabulary:5']);
+    $prophecy->getCacheContexts()->willReturn([]);
+    $prophecy->getCacheMaxAge()->willReturn(Cache::PERMANENT);
+    $vocab_storage = $this->getMock('Drupal\Core\Entity\EntityStorageInterface');
+    $vocab_storage->expects($this->any())
+      ->method('load')
+      ->will($this->returnValueMap(array(
+        array('forums', $prophecy->reveal()),
+      )));
+
+    $entity_manager = $this->getMockBuilder('Drupal\Core\Entity\EntityManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $entity_manager->expects($this->any())
+      ->method('getStorage')
+      ->will($this->returnValueMap(array(
+        array('taxonomy_vocabulary', $vocab_storage),
+      )));
+
+    $config_factory = $this->getConfigFactoryStub(
+      array(
+        'forum.settings' => array(
+          'vocabulary' => 'forums',
+        ),
+      )
+    );
+
+    // Build a breadcrumb builder to test.
+    $breadcrumb_builder = $this->getMock(
+      'Drupal\forum\Breadcrumb\ForumNodeBreadcrumbBuilder', NULL, array(
+        $entity_manager,
+        $config_factory,
+        $forum_manager,
+        $translation_manager,
+      )
+    );
+
+    // Add a translation manager for t().
+    $translation_manager = $this->getStringTranslationStub();
+    $property = new \ReflectionProperty('Drupal\forum\Breadcrumb\ForumNodeBreadcrumbBuilder', 'stringTranslation');
+    $property->setAccessible(TRUE);
+    $property->setValue($breadcrumb_builder, $translation_manager);
+
+    // The forum node we need a breadcrumb back from.
+    $forum_node = $this->getMockBuilder('Drupal\node\Entity\Node')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    // Our data set.
+    $route_match = $this->getMock('Drupal\Core\Routing\RouteMatchInterface');
+    $route_match->expects($this->exactly(2))
+      ->method('getParameter')
+      ->with('node')
+      ->will($this->returnValue($forum_node));
+
+    // First test.
+    $expected1 = array(
+      Link::createFromRoute('Home', '<front>'),
+      Link::createFromRoute('Forums', 'forum.index'),
+      Link::createFromRoute('Something', 'forum.page', array('taxonomy_term' => 1)),
+    );
+    $breadcrumb = $breadcrumb_builder->build($route_match);
+    $this->assertEquals($expected1, $breadcrumb->getLinks());
+    $this->assertEquals(['route'], $breadcrumb->getCacheContexts());
+    $this->assertEquals(['taxonomy_term:1', 'taxonomy_vocabulary:5'], $breadcrumb->getCacheTags());
+    $this->assertEquals(Cache::PERMANENT, $breadcrumb->getCacheMaxAge());
+
+    // Second test.
+    $expected2 = array(
+      Link::createFromRoute('Home', '<front>'),
+      Link::createFromRoute('Forums', 'forum.index'),
+      Link::createFromRoute('Something else', 'forum.page', array('taxonomy_term' => 2)),
+      Link::createFromRoute('Something', 'forum.page', array('taxonomy_term' => 1)),
+    );
+    $breadcrumb = $breadcrumb_builder->build($route_match);
+    $this->assertEquals($expected2, $breadcrumb->getLinks());
+    $this->assertEquals(['route'], $breadcrumb->getCacheContexts());
+    $this->assertEquals(['taxonomy_term:1', 'taxonomy_term:2', 'taxonomy_vocabulary:5'], $breadcrumb->getCacheTags());
+    $this->assertEquals(Cache::PERMANENT, $breadcrumb->getCacheMaxAge());
+  }
+
+}

web/core/modules/forum/tests/src/Unit/ForumManagerTest.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace Drupal\Tests\forum\Unit;
+
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\forum\ForumManager
+ * @group forum
+ */
+class ForumManagerTest extends UnitTestCase {
+
+  /**
+   * Tests ForumManager::getIndex().
+   */
+  public function testGetIndex() {
+    $entity_manager = $this->getMock('Drupal\Core\Entity\EntityManagerInterface');
+
+    $storage = $this->getMockBuilder('\Drupal\taxonomy\VocabularyStorage')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $config_factory = $this->getMock('\Drupal\Core\Config\ConfigFactoryInterface');
+
+    $config = $this->getMockBuilder('\Drupal\Core\Config\Config')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $config_factory->expects($this->once())
+      ->method('get')
+      ->will($this->returnValue($config));
+
+    $config->expects($this->once())
+      ->method('get')
+      ->will($this->returnValue('forums'));
+
+    $entity_manager->expects($this->once())
+      ->method('getStorage')
+      ->will($this->returnValue($storage));
+
+    // This is sufficient for testing purposes.
+    $term = new \stdClass();
+
+    $storage->expects($this->once())
+      ->method('create')
+      ->will($this->returnValue($term));
+
+    $connection = $this->getMockBuilder('\Drupal\Core\Database\Connection')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $translation_manager = $this->getMockBuilder('\Drupal\Core\StringTranslation\TranslationManager')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $comment_manager = $this->getMockBuilder('\Drupal\comment\CommentManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $manager = $this->getMock('\Drupal\forum\ForumManager', array('getChildren'), array(
+      $config_factory,
+      $entity_manager,
+      $connection,
+      $translation_manager,
+      $comment_manager,
+    ));
+
+    $manager->expects($this->once())
+      ->method('getChildren')
+      ->will($this->returnValue(array()));
+
+    // Get the index once.
+    $index1 = $manager->getIndex();
+
+    // Get it again. This should not return the previously generated index. If
+    // it does not, then the test will fail as the mocked methods will be called
+    // more than once.
+    $index2 = $manager->getIndex();
+
+    $this->assertEquals($index1, $index2);
+  }
+
+}

web/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php

@@ -0,0 +1,234 @@
+<?php
+
+namespace Drupal\Tests\forum\Unit;
+
+use Drupal\simpletest\AssertHelperTrait;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\forum\ForumUninstallValidator
+ * @group forum
+ */
+class ForumUninstallValidatorTest extends UnitTestCase {
+
+  use AssertHelperTrait;
+
+  /**
+   * @var \Drupal\forum\ForumUninstallValidator|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $forumUninstallValidator;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->forumUninstallValidator = $this->getMockBuilder('Drupal\forum\ForumUninstallValidator')
+      ->disableOriginalConstructor()
+      ->setMethods(['hasForumNodes', 'hasTermsForVocabulary', 'getForumVocabulary'])
+      ->getMock();
+    $this->forumUninstallValidator->setStringTranslation($this->getStringTranslationStub());
+  }
+
+  /**
+   * @covers ::validate
+   */
+  public function testValidateNotForum() {
+    $this->forumUninstallValidator->expects($this->never())
+      ->method('hasForumNodes');
+    $this->forumUninstallValidator->expects($this->never())
+      ->method('hasTermsForVocabulary');
+    $this->forumUninstallValidator->expects($this->never())
+      ->method('getForumVocabulary');
+
+    $module = 'not_forum';
+    $expected = [];
+    $reasons = $this->forumUninstallValidator->validate($module);
+    $this->assertSame($expected, $this->castSafeStrings($reasons));
+  }
+
+  /**
+   * @covers ::validate
+   */
+  public function testValidate() {
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasForumNodes')
+      ->willReturn(FALSE);
+
+    $vocabulary = $this->getMock('Drupal\taxonomy\VocabularyInterface');
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('getForumVocabulary')
+      ->willReturn($vocabulary);
+
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasTermsForVocabulary')
+      ->willReturn(FALSE);
+
+    $module = 'forum';
+    $expected = [];
+    $reasons = $this->forumUninstallValidator->validate($module);
+    $this->assertSame($expected, $this->castSafeStrings($reasons));
+  }
+
+  /**
+   * @covers ::validate
+   */
+  public function testValidateHasForumNodes() {
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasForumNodes')
+      ->willReturn(TRUE);
+
+    $vocabulary = $this->getMock('Drupal\taxonomy\VocabularyInterface');
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('getForumVocabulary')
+      ->willReturn($vocabulary);
+
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasTermsForVocabulary')
+      ->willReturn(FALSE);
+
+    $module = 'forum';
+    $expected = [
+      'To uninstall Forum, first delete all <em>Forum</em> content',
+    ];
+    $reasons = $this->forumUninstallValidator->validate($module);
+    $this->assertSame($expected, $this->castSafeStrings($reasons));
+  }
+
+  /**
+   * @covers ::validate
+   */
+  public function testValidateHasTermsForVocabularyWithNodesAccess() {
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasForumNodes')
+      ->willReturn(TRUE);
+
+    $vocabulary = $this->getMock('Drupal\taxonomy\VocabularyInterface');
+    $vocabulary->expects($this->once())
+      ->method('label')
+      ->willReturn('Vocabulary label');
+    $vocabulary->expects($this->once())
+      ->method('url')
+      ->willReturn('/path/to/vocabulary/overview');
+    $vocabulary->expects($this->once())
+      ->method('access')
+      ->willReturn(TRUE);
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('getForumVocabulary')
+      ->willReturn($vocabulary);
+
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasTermsForVocabulary')
+      ->willReturn(TRUE);
+
+    $module = 'forum';
+    $expected = [
+      'To uninstall Forum, first delete all <em>Forum</em> content',
+      'To uninstall Forum, first delete all <a href="/path/to/vocabulary/overview"><em class="placeholder">Vocabulary label</em></a> terms',
+    ];
+    $reasons = $this->forumUninstallValidator->validate($module);
+    $this->assertSame($expected, $this->castSafeStrings($reasons));
+  }
+
+  /**
+   * @covers ::validate
+   */
+  public function testValidateHasTermsForVocabularyWithNodesNoAccess() {
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasForumNodes')
+      ->willReturn(TRUE);
+
+    $vocabulary = $this->getMock('Drupal\taxonomy\VocabularyInterface');
+    $vocabulary->expects($this->once())
+      ->method('label')
+      ->willReturn('Vocabulary label');
+    $vocabulary->expects($this->never())
+      ->method('url');
+    $vocabulary->expects($this->once())
+      ->method('access')
+      ->willReturn(FALSE);
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('getForumVocabulary')
+      ->willReturn($vocabulary);
+
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasTermsForVocabulary')
+      ->willReturn(TRUE);
+
+    $module = 'forum';
+    $expected = [
+      'To uninstall Forum, first delete all <em>Forum</em> content',
+      'To uninstall Forum, first delete all <em class="placeholder">Vocabulary label</em> terms',
+    ];
+    $reasons = $this->forumUninstallValidator->validate($module);
+    $this->assertSame($expected, $this->castSafeStrings($reasons));
+  }
+
+  /**
+   * @covers ::validate
+   */
+  public function testValidateHasTermsForVocabularyAccess() {
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasForumNodes')
+      ->willReturn(FALSE);
+
+    $vocabulary = $this->getMock('Drupal\taxonomy\VocabularyInterface');
+    $vocabulary->expects($this->once())
+      ->method('url')
+      ->willReturn('/path/to/vocabulary/overview');
+    $vocabulary->expects($this->once())
+      ->method('label')
+      ->willReturn('Vocabulary label');
+    $vocabulary->expects($this->once())
+      ->method('access')
+      ->willReturn(TRUE);
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('getForumVocabulary')
+      ->willReturn($vocabulary);
+
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasTermsForVocabulary')
+      ->willReturn(TRUE);
+
+    $module = 'forum';
+    $expected = [
+      'To uninstall Forum, first delete all <a href="/path/to/vocabulary/overview"><em class="placeholder">Vocabulary label</em></a> terms',
+    ];
+    $reasons = $this->forumUninstallValidator->validate($module);
+    $this->assertSame($expected, $this->castSafeStrings($reasons));
+  }
+
+  /**
+   * @covers ::validate
+   */
+  public function testValidateHasTermsForVocabularyNoAccess() {
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasForumNodes')
+      ->willReturn(FALSE);
+
+    $vocabulary = $this->getMock('Drupal\taxonomy\VocabularyInterface');
+    $vocabulary->expects($this->once())
+      ->method('label')
+      ->willReturn('Vocabulary label');
+    $vocabulary->expects($this->never())
+      ->method('url');
+    $vocabulary->expects($this->once())
+      ->method('access')
+      ->willReturn(FALSE);
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('getForumVocabulary')
+      ->willReturn($vocabulary);
+
+    $this->forumUninstallValidator->expects($this->once())
+      ->method('hasTermsForVocabulary')
+      ->willReturn(TRUE);
+
+    $module = 'forum';
+    $expected = [
+      'To uninstall Forum, first delete all <em class="placeholder">Vocabulary label</em> terms',
+    ];
+    $reasons = $this->forumUninstallValidator->validate($module);
+    $this->assertSame($expected, $this->castSafeStrings($reasons));
+  }
+
+}