text: <?php
  
  /**
   * @file
   * Test module for testing the book module.
   *
   * This module's functionality depends on the following state variables:
   * - book_test.debug_book_navigation_cache_context: Used in NodeQueryAlterTest to enable the
   *   node_access_all grant realm.
   *
   * @see \Drupal\book\Tests\BookTest::testBookNavigationCacheContext()
   */
  
  /**
   * Implements hook_page_attachments().
   */
  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]);
    }
  }
  