updated core to 8.6.1 via composer

core/modules/book/book.es6.js

@@ -3,7 +3,7 @@
  * Javascript behaviors for the Book module.
  */
 
-(function ($, Drupal) {
+(function($, Drupal) {
   /**
    * Adds summaries to the book outline form.
    *
@@ -14,19 +14,21 @@
    */
   Drupal.behaviors.bookDetailsSummaries = {
     attach(context) {
-      $(context).find('.book-outline-form').drupalSetSummary((context) => {
-        const $select = $(context).find('.book-title-select');
-        const val = $select.val();
+      $(context)
+        .find('.book-outline-form')
+        .drupalSetSummary(context => {
+          const $select = $(context).find('.book-title-select');
+          const val = $select.val();
 
-        if (val === '0') {
-          return Drupal.t('Not in book');
-        }
-        else if (val === 'new') {
-          return Drupal.t('New book');
-        }
+          if (val === '0') {
+            return Drupal.t('Not in book');
+          }
+          if (val === 'new') {
+            return Drupal.t('New book');
+          }
 
-        return Drupal.checkPlain($select.find(':selected').text());
-      });
+          return Drupal.checkPlain($select.find(':selected').text());
+        });
     },
   };
-}(jQuery, Drupal));
+})(jQuery, Drupal);

core/modules/book/book.info.yml

@@ -5,5 +5,5 @@ package: Core
 version: VERSION
 core: 8.x
 dependencies:
-  - node
+  - drupal:node
 configure: book.settings

core/modules/book/book.js

@@ -14,7 +14,8 @@
 
         if (val === '0') {
           return Drupal.t('Not in book');
-        } else if (val === 'new') {
+        }
+        if (val === 'new') {
           return Drupal.t('New book');
         }
 

core/modules/book/book.libraries.yml

@@ -6,4 +6,3 @@ drupal.book:
     - core/jquery
     - core/drupal
     - core/drupal.form
-

core/modules/book/book.module

@@ -111,7 +111,7 @@ function book_node_links_alter(array &$links, NodeInterface $node, array &$conte
               'type' => 'html',
               'node' => $node->id(),
             ]),
-            'attributes' => ['title' => t('Show a printer-friendly version of this book page and its sub-pages.')]
+            'attributes' => ['title' => t('Show a printer-friendly version of this book page and its sub-pages.')],
           ];
         }
       }
@@ -539,3 +539,16 @@ function book_node_type_update(NodeTypeInterface $type) {
     $config->save();
   }
 }
+
+/**
+ * Implements hook_migration_plugins_alter().
+ */
+function book_migration_plugins_alter(array &$migrations) {
+  // Book settings are migrated identically for Drupal 6 and Drupal 7. However,
+  // a d6_book_settings migration already existed before the consolidated
+  // book_settings migration existed, so to maintain backwards compatibility,
+  // ensure that d6_book_settings is an alias of book_settings.
+  if (isset($migrations['book_settings'])) {
+    $migrations['d6_book_settings'] = &$migrations['book_settings'];
+  }
+}

core/modules/book/migrations/book_settings.yml

@@ -1,7 +1,8 @@
-id: d6_book_settings
+id: book_settings
 label: Book configuration
 migration_tags:
   - Drupal 6
+  - Drupal 7
   - Configuration
 source:
   plugin: variable

core/modules/book/migrations/d6_book.yml

@@ -4,7 +4,7 @@ migration_tags:
   - Drupal 6
   - Content
 source:
-  plugin: d6_book
+  plugin: book
 process:
   nid: nid
   'book/bid': bid

core/modules/book/migrations/d7_book.yml

@@ -0,0 +1,24 @@
+id: d7_book
+label: Books
+migration_tags:
+  - Drupal 7
+  - Content
+source:
+  plugin: book
+process:
+  nid: nid
+  'book/bid': bid
+  'book/weight': weight
+  'book/pid':
+    -
+      plugin: skip_on_empty
+      method: process
+      source: plid
+    -
+      plugin: migration_lookup
+      migration: d7_book
+destination:
+  plugin: book
+migration_dependencies:
+  required:
+    - d7_node

core/modules/book/src/BookManagerInterface.php

@@ -246,7 +246,8 @@ interface BookManagerInterface {
    *   A data structure representing the tree as returned from buildBookOutlineData.
    *
    * @return array
-   *   A structured array to be rendered by drupal_render().
+   *   A structured array to be rendered by
+   *   \Drupal\Core\Render\RendererInterface::render().
    *
    * @see \Drupal\Core\Menu\MenuLinkTree::build
    */

core/modules/book/src/BookOutlineStorageInterface.php

@@ -110,7 +110,6 @@ interface BookOutlineStorageInterface {
    */
   public function insert($link, $parents);
 
-
   /**
    * Updates book reference for links that were moved between books.
    *

core/modules/book/src/Controller/BookController.php

@@ -154,7 +154,7 @@ class BookController extends ControllerBase {
 
     // @todo Convert the custom export functionality to serializer.
     if (!method_exists($this->bookExport, $method)) {
-      drupal_set_message(t('Unknown export format.'));
+      $this->messenger()->addStatus(t('Unknown export format.'));
       throw new NotFoundHttpException();
     }
 

core/modules/book/src/Form/BookAdminEditForm.php

@@ -127,7 +127,7 @@ class BookAdminEditForm extends FormBase {
       }
     }
 
-    drupal_set_message($this->t('Updated book %title.', ['%title' => $form['#node']->label()]));
+    $this->messenger()->addStatus($this->t('Updated book %title.', ['%title' => $form['#node']->label()]));
   }
 
   /**

core/modules/book/src/Form/BookOutlineForm.php

@@ -5,7 +5,7 @@ namespace Drupal\book\Form;
 use Drupal\book\BookManagerInterface;
 use Drupal\Component\Datetime\TimeInterface;
 use Drupal\Core\Entity\ContentEntityForm;
-use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityRepositoryInterface;
 use Drupal\Core\Entity\EntityTypeBundleInfoInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Url;
@@ -35,8 +35,8 @@ class BookOutlineForm extends ContentEntityForm {
   /**
    * Constructs a BookOutlineForm object.
    *
-   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
-   *   The entity manager.
+   * @param \Drupal\Core\Entity\EntityRepositoryInterface $entity_repository
+   *   The entity repository.
    * @param \Drupal\book\BookManagerInterface $book_manager
    *   The BookManager service.
    * @param \Drupal\Core\Entity\EntityTypeBundleInfoInterface $entity_type_bundle_info
@@ -44,8 +44,8 @@ class BookOutlineForm extends ContentEntityForm {
    * @param \Drupal\Component\Datetime\TimeInterface $time
    *   The time service.
    */
-  public function __construct(EntityManagerInterface $entity_manager, BookManagerInterface $book_manager, EntityTypeBundleInfoInterface $entity_type_bundle_info = NULL, TimeInterface $time = NULL) {
-    parent::__construct($entity_manager, $entity_type_bundle_info, $time);
+  public function __construct(EntityRepositoryInterface $entity_repository, BookManagerInterface $book_manager, EntityTypeBundleInfoInterface $entity_type_bundle_info = NULL, TimeInterface $time = NULL) {
+    parent::__construct($entity_repository, $entity_type_bundle_info, $time);
     $this->bookManager = $book_manager;
   }
 
@@ -54,7 +54,7 @@ class BookOutlineForm extends ContentEntityForm {
    */
   public static function create(ContainerInterface $container) {
     return new static(
-      $container->get('entity.manager'),
+      $container->get('entity.repository'),
       $container->get('book.manager'),
       $container->get('entity_type.bundle.info'),
       $container->get('datetime.time')
@@ -113,7 +113,7 @@ class BookOutlineForm extends ContentEntityForm {
     );
     $book_link = $form_state->getValue('book');
     if (!$book_link['bid']) {
-      drupal_set_message($this->t('No changes were made'));
+      $this->messenger()->addStatus($this->t('No changes were made'));
       return;
     }
 
@@ -121,15 +121,15 @@ class BookOutlineForm extends ContentEntityForm {
     if ($this->bookManager->updateOutline($this->entity)) {
       if (isset($this->entity->book['parent_mismatch']) && $this->entity->book['parent_mismatch']) {
         // This will usually only happen when JS is disabled.
-        drupal_set_message($this->t('The post has been added to the selected book. You may now position it relative to other pages.'));
+        $this->messenger()->addStatus($this->t('The post has been added to the selected book. You may now position it relative to other pages.'));
         $form_state->setRedirectUrl($this->entity->urlInfo('book-outline-form'));
       }
       else {
-        drupal_set_message($this->t('The book outline has been updated.'));
+        $this->messenger()->addStatus($this->t('The book outline has been updated.'));
       }
     }
     else {
-      drupal_set_message($this->t('There was an error adding the post to the book.'), 'error');
+      $this->messenger()->addError($this->t('There was an error adding the post to the book.'));
     }
   }
 

core/modules/book/src/Form/BookRemoveForm.php

@@ -103,7 +103,7 @@ class BookRemoveForm extends ConfirmFormBase {
   public function submitForm(array &$form, FormStateInterface $form_state) {
     if ($this->bookManager->checkNodeIsRemovable($this->node)) {
       $this->bookManager->deleteFromBook($this->node->id());
-      drupal_set_message($this->t('The post has been removed from the book.'));
+      $this->messenger()->addStatus($this->t('The post has been removed from the book.'));
     }
     $form_state->setRedirectUrl($this->getCancelUrl());
   }

core/modules/book/src/Plugin/migrate/source/Book.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace Drupal\book\Plugin\migrate\source;
+
+use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
+
+/**
+ * Drupal 6 and 7 book source.
+ *
+ * @MigrateSource(
+ *   id = "book",
+ *   source_module = "book",
+ * )
+ */
+class Book extends DrupalSqlBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function query() {
+    $query = $this->select('book', 'b')->fields('b', ['nid', 'bid']);
+    $query->join('menu_links', 'ml', 'b.mlid = ml.mlid');
+    $ml_fields = ['mlid', 'plid', 'weight', 'has_children', 'depth'];
+    foreach (range(1, 9) as $i) {
+      $field = "p$i";
+      $ml_fields[] = $field;
+      $query->orderBy('ml.' . $field);
+    }
+    return $query->fields('ml', $ml_fields);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getIds() {
+    $ids['mlid']['type'] = 'integer';
+    $ids['mlid']['alias'] = 'ml';
+    return $ids;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function fields() {
+    return [
+      'nid' => $this->t('Node ID'),
+      'bid' => $this->t('Book ID'),
+      'mlid' => $this->t('Menu link ID'),
+      'plid' => $this->t('Parent link ID'),
+      'weight' => $this->t('Weight'),
+      'p1' => $this->t('The first mlid in the materialized path. If N = depth, then pN must equal the mlid. If depth > 1 then p(N-1) must equal the parent link mlid. All pX where X > depth must equal zero. The columns p1 .. p9 are also called the parents.'),
+      'p2' => $this->t('The second mlid in the materialized path. See p1.'),
+      'p3' => $this->t('The third mlid in the materialized path. See p1.'),
+      'p4' => $this->t('The fourth mlid in the materialized path. See p1.'),
+      'p5' => $this->t('The fifth mlid in the materialized path. See p1.'),
+      'p6' => $this->t('The sixth mlid in the materialized path. See p1.'),
+      'p7' => $this->t('The seventh mlid in the materialized path. See p1.'),
+      'p8' => $this->t('The eighth mlid in the materialized path. See p1.'),
+      'p9' => $this->t('The ninth mlid in the materialized path. See p1.'),
+    ];
+  }
+
+}

core/modules/book/src/Plugin/migrate/source/d6/Book.php

@@ -2,7 +2,9 @@
 
 namespace Drupal\book\Plugin\migrate\source\d6;
 
-use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
+use Drupal\book\Plugin\migrate\source\Book as BookGeneral;
+
+@trigger_error('Book is deprecated in Drupal 8.6.x and will be removed before Drupal 9.0.x. Use \Drupal\book\Plugin\migrate\source\Book instead. See https://www.drupal.org/node/2947487 for more information.', E_USER_DEPRECATED);
 
 /**
  * Drupal 6 book source.
@@ -11,54 +13,9 @@ use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
  *   id = "d6_book",
  *   source_module = "book"
  * )
+ *
+ * @deprecated in Drupal 8.6.x, to be removed before Drupal 9.0.x. Use
+ * \Drupal\book\Plugin\migrate\source\Book instead. See
+ * https://www.drupal.org/node/2947487 for more information.
  */
-class Book extends DrupalSqlBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function query() {
-    $query = $this->select('book', 'b')->fields('b', ['nid', 'bid']);
-    $query->join('menu_links', 'ml', 'b.mlid = ml.mlid');
-    $ml_fields = ['mlid', 'plid', 'weight', 'has_children', 'depth'];
-    for ($i = 1; $i <= 9; $i++) {
-      $field = "p$i";
-      $ml_fields[] = $field;
-      $query->orderBy('ml.' . $field);
-    }
-    $query->fields('ml', $ml_fields);
-    return $query;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getIds() {
-    $ids['mlid']['type'] = 'integer';
-    $ids['mlid']['alias'] = 'ml';
-    return $ids;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function fields() {
-    return [
-      'nid' => $this->t('Node ID'),
-      'bid' => $this->t('Book ID'),
-      'mlid' => $this->t('Menu link ID'),
-      'plid' => $this->t('Parent link ID'),
-      'weight' => $this->t('Weight'),
-      'p1' => $this->t('The first mlid in the materialized path. If N = depth, then pN must equal the mlid. If depth > 1 then p(N-1) must equal the parent link mlid. All pX where X > depth must equal zero. The columns p1 .. p9 are also called the parents.'),
-      'p2' => $this->t('The second mlid in the materialized path. See p1.'),
-      'p3' => $this->t('The third mlid in the materialized path. See p1.'),
-      'p4' => $this->t('The fourth mlid in the materialized path. See p1.'),
-      'p5' => $this->t('The fifth mlid in the materialized path. See p1.'),
-      'p6' => $this->t('The sixth mlid in the materialized path. See p1.'),
-      'p7' => $this->t('The seventh mlid in the materialized path. See p1.'),
-      'p8' => $this->t('The eighth mlid in the materialized path. See p1.'),
-      'p9' => $this->t('The ninth mlid in the materialized path. See p1.'),
-    ];
-  }
-
-}
+class Book extends BookGeneral {}

core/modules/book/tests/modules/book_test/book_test.module

@@ -17,6 +17,6 @@
 function book_test_page_attachments(array &$page) {
   $page['#cache']['tags'][] = 'book_test.debug_book_navigation_cache_context';
   if (\Drupal::state()->get('book_test.debug_book_navigation_cache_context', FALSE)) {
-    drupal_set_message(\Drupal::service('cache_contexts_manager')->convertTokensToKeys(['route.book_navigation'])->getKeys()[0]);
+    \Drupal::messenger()->addStatus(\Drupal::service('cache_contexts_manager')->convertTokensToKeys(['route.book_navigation'])->getKeys()[0]);
   }
 }

core/modules/book/tests/modules/book_test_views/book_test_views.info.yml

@@ -5,5 +5,5 @@ package: Testing
 version: VERSION
 core: 8.x
 dependencies:
- - book
- - views
+ - drupal:book
+ - drupal:views

core/modules/book/tests/src/Functional/BookContentModerationTest.php

@@ -3,7 +3,7 @@
 namespace Drupal\Tests\book\Functional;
 
 use Drupal\Tests\BrowserTestBase;
-use Drupal\workflows\Entity\Workflow;
+use Drupal\Tests\content_moderation\Traits\ContentModerationTestTrait;
 
 /**
  * Tests Book and Content Moderation integration.
@@ -13,6 +13,7 @@ use Drupal\workflows\Entity\Workflow;
 class BookContentModerationTest extends BrowserTestBase {
 
   use BookTestTrait;
+  use ContentModerationTestTrait;
 
   /**
    * Modules to install.
@@ -30,7 +31,7 @@ class BookContentModerationTest extends BrowserTestBase {
     $this->drupalPlaceBlock('system_breadcrumb_block');
     $this->drupalPlaceBlock('page_title_block');
 
-    $workflow = Workflow::load('editorial');
+    $workflow = $this->createEditorialWorkflow();
     $workflow->getTypePlugin()->addEntityTypeAndBundle('node', 'book');
     $workflow->save();
 

core/modules/book/tests/src/Functional/BookTestTrait.php

@@ -2,7 +2,7 @@
 
 namespace Drupal\Tests\book\Functional;
 
-use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Core\Entity\EntityInterface;
 
 /**
@@ -104,7 +104,7 @@ trait BookTestTrait {
       /** @var \Drupal\Core\Url $url */
       $url = $previous->urlInfo();
       $url->setOptions(['attributes' => ['rel' => ['prev'], 'title' => t('Go to previous page')]]);
-      $text = SafeMarkup::format('<b>‹</b> @label', ['@label' => $previous->label()]);
+      $text = new FormattableMarkup('<b>‹</b> @label', ['@label' => $previous->label()]);
       $this->assertRaw(\Drupal::l($text, $url), 'Previous page link found.');
     }
 
@@ -119,7 +119,7 @@ trait BookTestTrait {
       /** @var \Drupal\Core\Url $url */
       $url = $next->urlInfo();
       $url->setOptions(['attributes' => ['rel' => ['next'], 'title' => t('Go to next page')]]);
-      $text = SafeMarkup::format('@label <b>›</b>', ['@label' => $next->label()]);
+      $text = new FormattableMarkup('@label <b>›</b>', ['@label' => $next->label()]);
       $this->assertRaw(\Drupal::l($text, $url), 'Next page link found.');
     }
 

core/modules/book/tests/src/FunctionalJavascript/BookJavascriptTest.php

@@ -4,7 +4,7 @@ namespace Drupal\Tests\book\FunctionalJavascript;
 
 use Behat\Mink\Exception\ExpectationException;
 use Drupal\Component\Render\FormattableMarkup;
-use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
 use Drupal\node\Entity\Node;
 
 /**
@@ -12,7 +12,7 @@ use Drupal\node\Entity\Node;
  *
  * @group book
  */
-class BookJavascriptTest extends JavascriptTestBase {
+class BookJavascriptTest extends WebDriverTestBase {
 
   /**
    * {@inheritdoc}

core/modules/book/tests/src/Kernel/BookUninstallTest.php

@@ -76,7 +76,7 @@ class BookUninstallTest extends KernelTestBase {
 
     $book_node->delete();
     // No nodes exist therefore the book module is not required.
-    $module_data = _system_rebuild_module_data();
+    $module_data = \Drupal::service('extension.list.module')->reset()->getList();
     $this->assertFalse(isset($module_data['book']->info['required']), 'The book module is not required.');
 
     $node = Node::create(['title' => $this->randomString(), 'type' => $content_type->id()]);

core/modules/book/tests/src/Kernel/Migrate/d6/MigrateBookConfigsTest.php

@@ -20,17 +20,29 @@ class MigrateBookConfigsTest extends MigrateDrupal6TestBase {
   public static $modules = ['book'];
 
   /**
-   * {@inheritdoc}
+   * Data provider for testBookSettings().
+   *
+   * @return array
+   *   The data for each test scenario.
    */
-  protected function setUp() {
-    parent::setUp();
-    $this->executeMigration('d6_book_settings');
+  public function providerBookSettings() {
+    return [
+      // d6_book_settings was renamed to book_settings, but use the old alias to
+      // prove that it works.
+      // @see book_migration_plugins_alter()
+      ['d6_book_settings'],
+      ['book_settings'],
+    ];
   }
 
   /**
    * Tests migration of book variables to book.settings.yml.
+   *
+   * @dataProvider providerBookSettings
    */
-  public function testBookSettings() {
+  public function testBookSettings($migration_id) {
+    $this->executeMigration($migration_id);
+
     $config = $this->config('book.settings');
     $this->assertIdentical('book', $config->get('child_type'));
     $this->assertSame('book pages', $config->get('block.navigation.mode'));

core/modules/book/tests/src/Kernel/Migrate/d7/MigrateBookConfigsTest.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace Drupal\Tests\book\Kernel\Migrate\d7;
+
+use Drupal\Tests\migrate_drupal\Kernel\d7\MigrateDrupal7TestBase;
+use Drupal\Tests\SchemaCheckTestTrait;
+
+/**
+ * Tests the migration of Book settings.
+ *
+ * @group migrate_drupal_7
+ */
+class MigrateBookConfigsTest extends MigrateDrupal7TestBase {
+
+  use SchemaCheckTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['book', 'node'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->executeMigration('book_settings');
+  }
+
+  /**
+   * Tests migration of book variables to book.settings.yml.
+   */
+  public function testBookSettings() {
+    $config = $this->config('book.settings');
+    $this->assertSame('book', $config->get('child_type'));
+    $this->assertSame('all pages', $config->get('block.navigation.mode'));
+    $this->assertSame(['book'], $config->get('allowed_types'));
+    $this->assertConfigSchema(\Drupal::service('config.typed'), 'book.settings', $config->get());
+  }
+
+}

core/modules/book/tests/src/Kernel/Migrate/d7/MigrateBookTest.php

@@ -0,0 +1,69 @@
+<?php
+
+namespace Drupal\Tests\book\Kernel\Migrate\d7;
+
+use Drupal\Tests\migrate_drupal\Kernel\d7\MigrateDrupal7TestBase;
+use Drupal\node\Entity\Node;
+
+/**
+ * Tests migration of book structures from Drupal 7.
+ *
+ * @group migrate_drupal_7
+ */
+class MigrateBookTest extends MigrateDrupal7TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = [
+    'book',
+    'menu_ui',
+    'node',
+    'taxonomy',
+    'text',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->installEntitySchema('node');
+    $this->installEntitySchema('taxonomy_term');
+    $this->installConfig(['node']);
+    $this->installSchema('book', ['book']);
+    $this->installSchema('node', ['node_access']);
+    $this->executeMigrations([
+      'd7_user_role',
+      'd7_user',
+      'd7_node_type',
+      'd7_node',
+      'd7_book',
+    ]);
+  }
+
+  /**
+   * Tests the Drupal 7 book structure to Drupal 8 migration.
+   */
+  public function testBook() {
+    $nodes = Node::loadMultiple([1, 2, 4, 6]);
+    $this->assertSame('8', $nodes[1]->book['bid']);
+    $this->assertSame('6', $nodes[1]->book['pid']);
+
+    $this->assertSame('4', $nodes[2]->book['bid']);
+    $this->assertSame('6', $nodes[2]->book['pid']);
+
+    $this->assertSame('4', $nodes[4]->book['bid']);
+    $this->assertSame('0', $nodes[4]->book['pid']);
+
+    $this->assertSame('4', $nodes[6]->book['bid']);
+    $this->assertSame('4', $nodes[6]->book['pid']);
+
+    $tree = \Drupal::service('book.manager')->bookTreeAllData(4);
+    $this->assertSame('4', $tree['49990 is - The thing about Firefly 4']['link']['nid']);
+    $this->assertSame('6', $tree['49990 is - The thing about Firefly 4']['below']['50000 Comments are closed :-( 6']['link']['nid']);
+    $this->assertSame('2', $tree['49990 is - The thing about Firefly 4']['below']['50000 Comments are closed :-( 6']['below']['50000 The thing about Deep Space 9 2']['link']['nid']);
+    $this->assertSame([], $tree['49990 is - The thing about Firefly 4']['below']['50000 Comments are closed :-( 6']['below']['50000 The thing about Deep Space 9 2']['below']);
+  }
+
+}

core/modules/book/tests/src/Kernel/Plugin/migrate/source/BookTest.php

@@ -1,12 +1,14 @@
 <?php
 
-namespace Drupal\Tests\book\Kernel\Plugin\migrate\source\d6;
+namespace Drupal\Tests\book\Kernel\Plugin\migrate\source;
 
 use Drupal\Tests\migrate\Kernel\MigrateSqlSourceTestBase;
+use Drupal\book\Plugin\migrate\source\d6\Book as D6Book;
 
 /**
- * @covers \Drupal\book\Plugin\migrate\source\d6\Book
+ * @covers \Drupal\book\Plugin\migrate\source\Book
  * @group book
+ * @group legacy
  */
 class BookTest extends MigrateSqlSourceTestBase {
 
@@ -81,4 +83,18 @@ class BookTest extends MigrateSqlSourceTestBase {
     return $tests;
   }
 
+  /**
+   * @expectedDeprecation Book is deprecated in Drupal 8.6.x and will be removed before Drupal 9.0.x. Use \Drupal\book\Plugin\migrate\source\Book instead. See https://www.drupal.org/node/2947487 for more information.
+   */
+  public function testDeprecatedPlugin() {
+    new D6Book(
+      [],
+      'd6_book',
+      [],
+      $this->prophesize('Drupal\migrate\Plugin\MigrationInterface')->reveal(),
+      $this->prophesize('Drupal\Core\State\StateInterface')->reveal(),
+      $this->prophesize('Drupal\Core\Entity\EntityManagerInterface')->reveal()
+    );
+  }
+
 }