composer.json

@@ -9,7 +9,7 @@
         "chat": "https://www.drupal.org/node/314178"
     },
     "require": {
-        "composer/installers": "^1.9",
+        "composer/installers": "^2.0",
         "drupal/core": "self.version",
         "drupal/core-project-message": "self.version",
         "drupal/core-vendor-hardening": "self.version"

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "621f45e44e9dec8320bc3027e3408b8b",
+    "content-hash": "372c247b5fd3863e5f2b21cfca703dae",
     "packages": [
         {
             "name": "asm89/stack-cors",
@@ -64,38 +64,35 @@
         },
         {
             "name": "composer/installers",
-            "version": "v1.12.0",
+            "version": "v2.0.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/composer/installers.git",
-                "reference": "d20a64ed3c94748397ff5973488761b22f6d3f19"
+                "reference": "a241e78aaeb09781f5f5b92ac01ffd13ab43e5e8"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/composer/installers/zipball/d20a64ed3c94748397ff5973488761b22f6d3f19",
-                "reference": "d20a64ed3c94748397ff5973488761b22f6d3f19",
+                "url": "https://api.github.com/repos/composer/installers/zipball/a241e78aaeb09781f5f5b92ac01ffd13ab43e5e8",
+                "reference": "a241e78aaeb09781f5f5b92ac01ffd13ab43e5e8",
                 "shasum": ""
             },
             "require": {
-                "composer-plugin-api": "^1.0 || ^2.0"
-            },
-            "replace": {
-                "roundcube/plugin-installer": "*",
-                "shama/baton": "*"
+                "composer-plugin-api": "^1.0 || ^2.0",
+                "php": "^7.2 || ^8.0"
             },
             "require-dev": {
                 "composer/composer": "1.6.* || ^2.0",
                 "composer/semver": "^1 || ^3",
                 "phpstan/phpstan": "^0.12.55",
                 "phpstan/phpstan-phpunit": "^0.12.16",
-                "symfony/phpunit-bridge": "^4.2 || ^5",
-                "symfony/process": "^2.3"
+                "symfony/phpunit-bridge": "^5.3",
+                "symfony/process": "^5"
             },
             "type": "composer-plugin",
             "extra": {
                 "class": "Composer\\Installers\\Plugin",
                 "branch-alias": {
-                    "dev-main": "1.x-dev"
+                    "dev-main": "2.x-dev"
                 }
             },
             "autoload": {
@@ -117,7 +114,6 @@
             "description": "A multi-framework Composer library installer",
             "homepage": "https://composer.github.io/installers/",
             "keywords": [
-                "Craft",
                 "Dolibarr",
                 "Eliasis",
                 "Hurad",
@@ -138,7 +134,6 @@
                 "Whmcs",
                 "WolfCMS",
                 "agl",
-                "aimeos",
                 "annotatecms",
                 "attogram",
                 "bitrix",
@@ -157,7 +152,6 @@
                 "grav",
                 "installer",
                 "itop",
-                "joomla",
                 "known",
                 "kohana",
                 "laravel",
@@ -185,9 +179,7 @@
                 "silverstripe",
                 "sydes",
                 "sylius",
-                "symfony",
                 "tastyigniter",
-                "typo3",
                 "wordpress",
                 "yawik",
                 "zend",
@@ -195,7 +187,7 @@
             ],
             "support": {
                 "issues": "https://github.com/composer/installers/issues",
-                "source": "https://github.com/composer/installers/tree/v1.12.0"
+                "source": "https://github.com/composer/installers/tree/v2.0.1"
             },
             "funding": [
                 {
@@ -211,7 +203,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-09-13T08:19:44+00:00"
+            "time": "2021-09-13T08:21:20+00:00"
         },
         {
             "name": "composer/semver",

composer/Plugin/Scaffold/README.md

@@ -383,7 +383,7 @@ Sample composer.json for a project that relies on packages that use composer-sca
   "name": "my/project",
   "require": {
     "drupal/core-composer-scaffold": "*",
-    "composer/installers": "^1.9",
+    "composer/installers": "^2.0",
     "cweagans/composer-patches": "^1.6.5",
     "drupal/core": "^8.8.x-dev",
     "service-provider/d8-scaffold-files": "^1"

composer/Template/LegacyProject/composer.json

@@ -15,7 +15,7 @@
         }
     ],
     "require": {
-        "composer/installers": "^1.9",
+        "composer/installers": "^2.0",
         "drupal/core-composer-scaffold": "^10.0",
         "drupal/core-project-message": "^10.0",
         "drupal/core-recommended": "^10.0",

composer/Template/RecommendedProject/composer.json

@@ -15,7 +15,7 @@
         }
     ],
     "require": {
-        "composer/installers": "^1.9",
+        "composer/installers": "^2.0",
         "drupal/core-composer-scaffold": "^10.0",
         "drupal/core-project-message": "^10.0",
         "drupal/core-recommended": "^10.0"

core/lib/Drupal.php

@@ -96,7 +96,7 @@ class Drupal {
    *   that Drupal no longer supports that PHP version.
    * - An error is shown in the status report that the PHP version is too old.
    */
-  const MINIMUM_SUPPORTED_PHP = '8.0.2';
+  const MINIMUM_SUPPORTED_PHP = '8.1.0';
 
   /**
    * Minimum allowed version of PHP for Drupal to be bootstrapped.

core/modules/ckeditor5/ckeditor5.libraries.yml

@@ -29,8 +29,17 @@ drupal.ckeditor5:
     - core/ckeditor5.editorDecoupled
     - core/ckeditor5
     - editor/drupal.editor
-    - ckeditor5/drupal.ckeditor5.quickedit-temporary-work-around
     - ckeditor5/ie11.user.warnings
+    - ckeditor5/drupal.ckeditor5.stylesheets
+    - core/drupalSettings
+    - core/drupal.message
+
+# Library used for dynamically loading CKEditor 5 stylesheets from the default
+# front end theme.
+# @see ckeditor5_library_info_alter()
+drupal.ckeditor5.stylesheets:
+  version: VERSION
+  css: []
 
 drupal.ckeditor5.quickedit-temporary-work-around:
   deprecated: "Temporary work-around until https://www.drupal.org/project/drupal/issues/3196689 lands."
@@ -103,6 +112,8 @@ drupal.ckeditor5.filter.admin:
     - core/drupal.message
     - core/once
     - core/drupal.ajax
+    - core/drupalSettings
+    - core/drupal.message
 
 admin:
   js:

core/modules/ckeditor5/ckeditor5.module

@@ -8,6 +8,7 @@
 declare(strict_types = 1);
 
 use Drupal\ckeditor5\Plugin\Editor\CKEditor5;
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Ajax\AjaxResponse;
 use Drupal\Core\Ajax\InvokeCommand;
 use Drupal\Core\Ajax\MessageCommand;
@@ -392,6 +393,22 @@ function ckeditor5_library_info_alter(&$libraries, $extension) {
   }
 
   $moduleHandler = \Drupal::moduleHandler();
+
+  if ($extension === 'ckeditor5') {
+    // Add paths to stylesheets specified by a theme's ckeditor5-stylesheets
+    // config property.
+    $css = _ckeditor5_theme_css();
+    $libraries['drupal.ckeditor5.stylesheets'] = [
+      'css' => [
+        'theme' => array_fill_keys(array_values($css), []),
+      ],
+    ];
+
+    if ($moduleHandler->moduleExists('quickedit')) {
+      $libraries['drupal.ckeditor5']['dependencies'][] = 'ckeditor5/drupal.ckeditor5.quickedit-temporary-work-around';
+    }
+  }
+
   // Only add translation processing if the locale module is enabled.
   if (!$moduleHandler->moduleExists('locale')) {
     return;
@@ -558,3 +575,44 @@ function ckeditor5_config_schema_info_alter(&$definitions) {
   // @see @see editor.editor.*.image_upload
   $definitions['ckeditor5_valid_pair__format_and_editor']['mapping']['image_upload'] = $definitions['editor.editor.*']['mapping']['image_upload'];
 }
+
+/**
+ * Retrieves the default theme's CKEditor 5 stylesheets.
+ *
+ * Themes may specify CSS files for use within CKEditor 5 by including a
+ * "ckeditor5-stylesheets" key in their .info.yml file.
+ *
+ * @code
+ * ckeditor5-stylesheets:
+ *   - css/ckeditor.css
+ * @endcode
+ *
+ * @return string[]
+ *   A list of paths to CSS files.
+ */
+function _ckeditor5_theme_css($theme = NULL): array {
+  $css = [];
+  if (!isset($theme)) {
+    $theme = \Drupal::config('system.theme')->get('default');
+  }
+  if (isset($theme) && $theme_path = \Drupal::service('extension.list.theme')->getPath($theme)) {
+    $info = \Drupal::service('extension.list.theme')->getExtensionInfo($theme);
+    if (isset($info['ckeditor5-stylesheets'])) {
+      $css = $info['ckeditor5-stylesheets'];
+      foreach ($css as $key => $url) {
+        // CSS url is external or relative to Drupal root.
+        if (UrlHelper::isExternal($url) || $url[0] === '/') {
+          $css[$key] = $url;
+        }
+        // CSS url is relative to theme.
+        else {
+          $css[$key] = '/' . $theme_path . '/' . $url;
+        }
+      }
+    }
+    if (isset($info['base theme'])) {
+      $css = array_merge(_ckeditor5_theme_css($info['base theme']), $css);
+    }
+  }
+  return $css;
+}

core/modules/ckeditor5/ckeditor5.services.yml

@@ -13,3 +13,13 @@ services:
       - '@plugin.manager.ckeditor5.plugin'
       - '@plugin.manager.ckeditor4to5upgrade.plugin'
       - '@?plugin.manager.ckeditor.plugin'
+  ckeditor5.stylesheets.message:
+    class: Drupal\ckeditor5\CKEditor5StylesheetsMessage
+    arguments:
+      - '@theme_handler'
+      - '@config.factory'
+  ckeditor5.ckeditor5_cache_tag:
+    class: Drupal\ckeditor5\EventSubscriber\CKEditor5CacheTag
+    arguments: ['@cache_tags.invalidator']
+    tags:
+      - { name: event_subscriber }

core/modules/ckeditor5/js/ie11.filter.warnings.es6.js

@@ -24,7 +24,7 @@
 
         // Add a container for messages above the text format select element.
         const selectMessageContainer = document.createElement('div');
-        select.parentNode.insertBefore(selectMessageContainer, select);
+        select.parentNode.after(selectMessageContainer, select);
         const selectMessages = new Drupal.Message(selectMessageContainer);
         const editorSettings = document.querySelector(
           '#editor-settings-wrapper',

core/modules/ckeditor5/js/ie11.filter.warnings.js

@@ -14,7 +14,7 @@
       if (typeof editorSelect[0] !== 'undefined') {
         const select = editorSelect[0];
         const selectMessageContainer = document.createElement('div');
-        select.parentNode.insertBefore(selectMessageContainer, select);
+        select.parentNode.after(selectMessageContainer, select);
         const selectMessages = new Drupal.Message(selectMessageContainer);
         const editorSettings = document.querySelector('#editor-settings-wrapper');
 

core/modules/ckeditor5/src/CKEditor5StylesheetsMessage.php

+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\ckeditor5;
+
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Extension\ThemeHandlerInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+
+/**
+ * Messaging for themes using the ckeditor_stylesheets setting.
+ *
+ * Messaging is provided when themes are found that use ckeditor_stylesheets
+ * without a corresponding ckeditor5-stylesheets setting.
+ *
+ * @internal
+ *   This class may change at any time. It is not for use outside this module.
+ * @todo Remove in Drupal 11: https://www.drupal.org/project/ckeditor5/issues/3239012
+ */
+final class CKEditor5StylesheetsMessage {
+
+  use StringTranslationTrait;
+
+  /**
+   * The theme handler.
+   *
+   * @var \Drupal\Core\Extension\ThemeHandlerInterface
+   */
+  protected $themeHandler;
+
+  /**
+   * The config factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * Constructs a new CKEditor5StylesheetsMessage.
+   *
+   * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
+   *   The theme handler.
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The config factory to get the installed themes.
+   */
+  public function __construct(ThemeHandlerInterface $theme_handler, ConfigFactoryInterface $config_factory) {
+    $this->themeHandler = $theme_handler;
+    $this->configFactory = $config_factory;
+  }
+
+  /**
+   * Generates a warning related to ckeditor_stylesheets.
+   *
+   * Identifies themes using ckeditor_stylesheets without an equivalent
+   * ckeditor5-stylesheets setting. If such themes are found, a warning message
+   * is returned.
+   *
+   * @return \Drupal\Core\StringTranslation\PluralTranslatableMarkup|null
+   *   A warning message where appropriate, otherwise null.
+   */
+  public function getWarning() {
+    $themes = [];
+    $default_theme = $this->configFactory->get('system.theme')->get('default');
+    if (!empty($default_theme)) {
+      $themes[$default_theme] = $this->themeHandler->listInfo()[$default_theme]->info;
+    }
+
+    $admin_theme = $this->configFactory->get('system.theme')->get('admin');
+    if (!empty($admin_theme) && $admin_theme !== $default_theme) {
+      $themes[$admin_theme] = $this->themeHandler->listInfo()[$admin_theme]->info;
+    }
+
+    // Collect information on which themes/base themes have ckeditor_stylesheets
+    // configuration, but do not have corresponding ckeditor5-stylesheets
+    // configuration.
+    $ckeditor_stylesheets_use = [];
+    foreach ($themes as $theme_info) {
+      $this->checkForStylesheetsEquivalent($theme_info, $ckeditor_stylesheets_use);
+    }
+
+    if (!empty($ckeditor_stylesheets_use)) {
+      // A subtheme may unnecessarily appear multiple times.
+      $ckeditor_stylesheets_use = array_unique($ckeditor_stylesheets_use);
+      $last_item = array_pop($ckeditor_stylesheets_use);
+      $stylesheets_warning = $this->formatPlural(count($ckeditor_stylesheets_use) + 1,
+        'The %last_item theme has ckeditor_stylesheets configured without a corresponding ckeditor5-stylesheets configuration. See the <a href=":change_record">change record</a> for details.',
+        'The %first_items and %last_item themes have ckeditor_stylesheets configured, but without corresponding ckeditor5-stylesheets configurations. See the <a href=":change_record">change record</a> for details.',
+        [
+          '%last_item' => $last_item,
+          '%first_items' => implode(', ', $ckeditor_stylesheets_use),
+          ':change_record' => 'https://www.drupal.org/node/3259165',
+        ]);
+
+      return $stylesheets_warning;
+    }
+
+    return NULL;
+  }
+
+  /**
+   * Checks themes using ckeditor_stylesheets for CKEditor 5 equivalents.
+   *
+   * @param array $theme_info
+   *   The config of the theme to check.
+   * @param string[] $ckeditor_stylesheets_use
+   *   Themes using ckeditor_stylesheets without a CKEditor 5 equivalent.
+   */
+  private function checkForStylesheetsEquivalent(array $theme_info, array &$ckeditor_stylesheets_use) {
+    $theme_has_ckeditor5_stylesheets = isset($theme_info['ckeditor5-stylesheets']);
+    if (!empty($theme_info['ckeditor_stylesheets']) && !$theme_has_ckeditor5_stylesheets) {
+      $ckeditor_stylesheets_use[] = $theme_info['name'];
+    }
+
+    // If the primary theme has ckeditor5-stylesheets configured, do not check
+    // base themes. The primary theme can potentially provide the
+    // ckeditor5-stylesheets config for itself and its base themes, so we err
+    // on the side of not showing a warning if this is possibly the case.
+    if ($theme_has_ckeditor5_stylesheets) {
+      return;
+    }
+    $base_theme = $theme_info['base theme'] ?? FALSE;
+    while ($base_theme) {
+      $base_theme_info = $this->themeHandler->listInfo()[$base_theme]->info;
+      $base_theme_has_ckeditor5_stylesheets = isset($base_theme_info['ckeditor5-stylesheets']);
+
+      if (!empty($base_theme_info['ckeditor_stylesheets']) && !$base_theme_has_ckeditor5_stylesheets) {
+        $ckeditor_stylesheets_use[] = $base_theme_info['name'];
+      }
+      $base_theme = $base_theme_info['base theme'] ?? FALSE;
+    }
+  }
+
+}

core/modules/ckeditor5/src/EventSubscriber/CKEditor5CacheTag.php

+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\ckeditor5\EventSubscriber;
+
+use Drupal\Core\Cache\CacheTagsInvalidatorInterface;
+use Drupal\Core\Config\ConfigCrudEvent;
+use Drupal\Core\Config\ConfigEvents;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * A subscriber invalidating cache tags when the default theme changes.
+ *
+ * @internal
+ *   This class may change at any time. It is not for use outside this module.
+ */
+class CKEditor5CacheTag implements EventSubscriberInterface {
+
+  /**
+   * The cache tags invalidator.
+   *
+   * @var \Drupal\Core\Cache\CacheTagsInvalidatorInterface
+   */
+  protected $cacheTagsInvalidator;
+
+  /**
+   * Constructs a CKEditor5CacheTag object.
+   *
+   * @param \Drupal\Core\Cache\CacheTagsInvalidatorInterface $cache_tags_invalidator
+   *   The cache tags invalidator.
+   */
+  public function __construct(CacheTagsInvalidatorInterface $cache_tags_invalidator) {
+    $this->cacheTagsInvalidator = $cache_tags_invalidator;
+  }
+
+  /**
+   * Invalidates cache tags when particular system config objects are saved.
+   *
+   * @param \Drupal\Core\Config\ConfigCrudEvent $event
+   *   The Event to process.
+   */
+  public function onSave(ConfigCrudEvent $event) {
+    $config_name = $event->getConfig()->getName();
+
+    // Ckeditor5-stylesheets settings may change when the default theme changes.
+    if ($config_name === 'system.theme' && $event->isChanged('default')) {
+      // @see ckeditor5_library_info_alter()
+      $this->cacheTagsInvalidator->invalidateTags(['library_info']);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    $events[ConfigEvents::SAVE][] = ['onSave'];
+    return $events;
+  }
+
+}

core/modules/ckeditor5/src/Plugin/Editor/CKEditor5.php

@@ -4,6 +4,7 @@
 
 namespace Drupal\ckeditor5\Plugin\Editor;
 
+use Drupal\ckeditor5\CKEditor5StylesheetsMessage;
 use Drupal\ckeditor5\HTMLRestrictions;
 use Drupal\ckeditor5\Plugin\CKEditor5Plugin\Heading;
 use Drupal\ckeditor5\Plugin\CKEditor5PluginDefinition;
@@ -98,6 +99,13 @@ class CKEditor5 extends EditorBase implements ContainerFactoryPluginInterface {
    */
   protected $cache;
 
+  /**
+   * The ckeditor_stylesheets message utility.
+   *
+   * @var \Drupal\ckeditor5\CKEditor5StylesheetsMessage
+   */
+  private $stylesheetsMessage;
+
   /**
    * Constructs a CKEditor5 editor plugin.
    *
@@ -117,14 +125,17 @@ class CKEditor5 extends EditorBase implements ContainerFactoryPluginInterface {
    *   The smart default settings utility.
    * @param \Drupal\Core\Cache\CacheBackendInterface $cache
    *   The cache.
+   * @param \Drupal\ckeditor5\CKEditor5StylesheetsMessage $stylesheets_message
+   *   The ckeditor_stylesheets message utility.
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, CKEditor5PluginManagerInterface $ckeditor5_plugin_manager, LanguageManagerInterface $language_manager, ModuleHandlerInterface $module_handler, SmartDefaultSettings $smart_default_settings, CacheBackendInterface $cache) {
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, CKEditor5PluginManagerInterface $ckeditor5_plugin_manager, LanguageManagerInterface $language_manager, ModuleHandlerInterface $module_handler, SmartDefaultSettings $smart_default_settings, CacheBackendInterface $cache, CKEditor5StylesheetsMessage $stylesheets_message) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
     $this->ckeditor5PluginManager = $ckeditor5_plugin_manager;
     $this->languageManager = $language_manager;
     $this->moduleHandler = $module_handler;
     $this->smartDefaultSettings = $smart_default_settings;
     $this->cache = $cache;
+    $this->stylesheetsMessage = $stylesheets_message;
   }
 
   /**
@@ -139,7 +150,8 @@ public static function create(ContainerInterface $container, array $configuratio
       $container->get('language_manager'),
       $container->get('module_handler'),
       $container->get('ckeditor5.smart_default_settings'),
-      $container->get('cache.default')
+      $container->get('cache.default'),
+      $container->get('ckeditor5.stylesheets.message')
     );
   }
 
@@ -267,6 +279,23 @@ public function buildConfigurationForm(array $form, FormStateInterface $form_sta
       $form_state->set('editor', $editor);
     }
 
+    if ($css_warning = $this->stylesheetsMessage->getWarning()) {
+      // Explicitly render this single warning message visually close to the
+      // text editor since this is a very long form. Otherwise, it may be
+      // interpreted as a text format problem, or ignored entirely.
+      // All other messages will be rendered in the default location.
+      // @see \Drupal\Core\Render\Element\StatusMessages
+      $form['css_warning'] = [
+        '#theme' => 'status_messages',
+        '#message_list' => [
+          'warning' => [$css_warning],
+        ],
+        '#status_headings' => [
+          'warning' => t('Warning message'),
+        ],
+      ];
+    }
+
     // AJAX validation errors should appear visually close to the text editor
     // since this is a very long form: otherwise they would not be noticed.
     $form['real_time_validation_errors_location'] = [

core/modules/ckeditor5/tests/src/Functional/AddedStylesheetsTest.php

+<?php
+
+namespace Drupal\Tests\ckeditor5\Functional;
+
+use Drupal\ckeditor5\Plugin\Editor\CKEditor5;
+use Drupal\editor\Entity\Editor;
+use Drupal\filter\Entity\FilterFormat;
+use Drupal\Tests\BrowserTestBase;
+use Drupal\user\RoleInterface;
+use Symfony\Component\Validator\ConstraintViolation;
+
+/**
+ * Test the ckeditor5-stylesheets theme config property.
+ *
+ * @group ckeditor5
+ */
+class AddedStylesheetsTest extends BrowserTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'node',
+    'ckeditor5',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $filtered_html_format = FilterFormat::create([
+      'format' => 'llama',
+      'name' => 'Llama',
+      'filters' => [],
+      'roles' => [RoleInterface::AUTHENTICATED_ID],
+    ]);
+    $filtered_html_format->save();
+    $this->editor = Editor::create([
+      'format' => 'llama',
+      'editor' => 'ckeditor5',
+      'settings' => [
+        'toolbar' => [
+          'items' => [],
+        ],
+      ],
+    ]);
+    $this->editor->save();
+    $this->assertSame([], array_map(
+      function (ConstraintViolation $v) {
+        return (string) $v->getMessage();
+      },
+      iterator_to_array(CKEditor5::validatePair($this->editor, $filtered_html_format))
+    ));
+    // Create node type.
+    $this->drupalCreateContentType([
+      'type' => 'article',
+      'name' => 'Article',
+    ]);
+
+    $this->adminUser = $this->drupalCreateUser([
+      'create article content',
+      'use text format llama',
+      'administer themes',
+      'view the administration theme',
+    ]);
+    $this->drupalLogin($this->adminUser);
+  }
+
+  /**
+   * Test the ckeditor5-stylesheets theme config.
+   */
+  public function testCkeditorStylesheets() {
+    $assert_session = $this->assertSession();
+
+    /** @var \Drupal\Core\Extension\ThemeInstallerInterface $theme_installer */
+    $theme_installer = \Drupal::service('theme_installer');
+    $theme_installer->install(['test_ckeditor_stylesheets_relative', 'seven']);
+    $this->config('system.theme')->set('admin', 'seven')->save();
+    $this->config('node.settings')->set('use_admin_theme', TRUE)->save();
+
+    $this->drupalGet('node/add/article');
+    $assert_session->responseNotContains('test_ckeditor_stylesheets_relative/css/yokotsoko.css');
+
+    // Install a theme with ckeditor5-stylesheets configured. Do this manually
+    // to confirm `library_info` cache tags are invalidated.
+    $this->drupalGet('admin/appearance');
+    $this->clickLink('Set Test relative CKEditor stylesheets as default theme');
+
+    // Confirm the stylesheet added via `ckeditor5-stylesheets` is present.
+    $this->drupalGet('node/add/article');
+    $assert_session->responseContains('test_ckeditor_stylesheets_relative/css/yokotsoko.css');
+
+    // Change the default theme to Stark, and confirm the stylesheet added via
+    // `ckeditor5-stylesheets` is no longer present.
+    $this->drupalGet('admin/appearance');
+    $this->clickLink('Set Stark as default theme');
+    $this->drupalGet('node/add/article');
+    $assert_session->responseNotContains('test_ckeditor_stylesheets_relative/css/yokotsoko.css');
+  }
+
+}

core/modules/ckeditor5/tests/src/Functional/CKEditor5QuickEditLibraryTest.php

+<?php
+
+namespace Drupal\Tests\ckeditor5\Functional;
+
+use Drupal\ckeditor5\Plugin\Editor\CKEditor5;
+use Drupal\editor\Entity\Editor;
+use Drupal\filter\Entity\FilterFormat;
+use Drupal\Tests\BrowserTestBase;
+use Drupal\user\RoleInterface;
+use Symfony\Component\Validator\ConstraintViolation;
+
+/**
+ * Tests that a Quick Edit specific library loads when Quick Edit is enabled.
+ *
+ * @group ckeditor5
+ * @group legacy
+ */
+class CKEditor5QuickEditLibraryTest extends BrowserTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'node',
+    'ckeditor5',
+    'quickedit',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $format = FilterFormat::create([
+      'format' => 'llama',
+      'name' => 'Llama',
+      'filters' => [],
+      'roles' => [RoleInterface::AUTHENTICATED_ID],
+    ]);
+    $format->save();
+    $editor = Editor::create([
+      'format' => 'llama',
+      'editor' => 'ckeditor5',
+      'settings' => [
+        'toolbar' => [
+          'items' => [],
+        ],
+      ],
+    ]);
+    $editor->save();
+    $this->assertSame([], array_map(
+      function (ConstraintViolation $v) {
+        return (string) $v->getMessage();
+      },
+      iterator_to_array(CKEditor5::validatePair($editor, $format))
+    ));
+    $this->drupalCreateContentType([
+      'type' => 'article',
+      'name' => 'Article',
+    ]);
+
+    $this->adminUser = $this->drupalCreateUser([
+      'create article content',
+      'use text format llama',
+    ]);
+    $this->drupalLogin($this->adminUser);
+  }
+
+  /**
+   * Tests that the Quick Edit workaround CSS loads when needed.
+   */
+  public function testQuickeditTemporaryWorkaround() {
+    $assert_session = $this->assertSession();
+
+    $this->expectDeprecation('Temporary work-around until https://www.drupal.org/project/drupal/issues/3196689 lands.');
+
+    $this->drupalGet('node/add/article');
+    $assert_session->responseContains('css/quickedit-override.css');
+  }
+
+}

core/modules/ckeditor5/tests/src/FunctionalJavascript/CKEditorStylesheetsWarningTest.php

+<?php
+
+namespace Drupal\Tests\ckeditor5\FunctionalJavascript;
+
+// cspell:ignore subtheming
+
+/**
+ * Tests warnings when ckeditor_stylesheets do not have CKEditor 5 equivalents.
+ *
+ * @group ckeditor5
+ * @internal
+ */
+class CKEditorStylesheetsWarningTest extends CKEditor5TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+  }
+
+  /**
+   * Installs and enables themes for testing.
+   *
+   * @param string $theme
+   *   The theme to enable.
+   */
+  public function installThemeThatTriggersWarning($theme) {
+    $theme_installer = \Drupal::service('theme_installer');
+    $theme_installer->install([$theme]);
+    $this->config('system.theme')->set('default', $theme)->save();
+    $theme_installer->install(['stark']);
+    $this->config('system.theme')->set('admin', 'stark')->save();
+    \Drupal::service('theme_handler')->refreshInfo();
+  }
+
+  /**
+   * Test the ckeditor_stylesheets warning in the filter UI.
+   *
+   * @dataProvider providerTestWarningFilterUI
+   */
+  public function testWarningFilterUi($theme, $expected_warning) {
+    $page = $this->getSession()->getPage();
+    $assert_session = $this->assertSession();
+    $this->addNewTextFormat($page, $assert_session);
+    $this->drupalGet('admin/config/content/formats/manage/ckeditor5');
+
+    $assert_session->pageTextNotContains($expected_warning);
+    $this->installThemeThatTriggersWarning($theme);
+    $this->drupalGet('admin/config/content/formats/manage/ckeditor5');
+    $this->assertTrue($assert_session->waitForText($expected_warning));
+  }
+
+  /**
+   * Data provider for testWarningFilterUI().
+   *
+   * @return \string[][]
+   *   An array with the theme to enable and the warning message to check.
+   */
+  public function providerTestWarningFilterUi() {
+    return [
+      'single theme' => [
+        'theme' => 'test_ckeditor_stylesheets_without_5',
+        'expected_warning' => 'The No setting for CKEditor 5 stylesheets theme has ckeditor_stylesheets configured without a corresponding ckeditor5-stylesheets configuration. See the change record for details.',
+      ],
+      'with base theme' => [
+        'theme' => 'test_subtheming_ckeditor_stylesheets_without_5',
+        'expected_warning' => 'The No setting for CKEditor 5 stylesheets here or subtheme and No setting for CKEditor 5 stylesheets themes have ckeditor_stylesheets configured, but without corresponding ckeditor5-stylesheets configurations. See the change record for details.',
+      ],
+    ];
+  }
+
+}

core/modules/ckeditor5/tests/src/Kernel/CKEditor5StylesheetsTest.php

+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\Tests\ckeditor5\Kernel;
+
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Test the ckeditor5-stylesheets theme config property.
+ *
+ * @group ckeditor5
+ */
+class CKEditor5StylesheetsTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'system',
+    'user',
+    'ckeditor5',
+    'editor',
+    'filter',
+  ];
+
+  /**
+   * Tests loading of theme's CKEditor 5 stylesheets defined in the .info file.
+   *
+   * @param string $theme
+   *   The machine name of the theme.
+   * @param array $expected
+   *   The expected CKEditor 5 CSS paths from the theme.
+   *
+   * @dataProvider externalStylesheetsProvider
+   */
+  public function testExternalStylesheets($theme, $expected) {
+    \Drupal::service('theme_installer')->install([$theme]);
+    $this->config('system.theme')->set('default', $theme)->save();
+    $this->assertSame($expected, _ckeditor5_theme_css($theme));
+  }
+
+  /**
+   * Provides test cases for external stylesheets.
+   *
+   * @return array
+   *   An array of test cases.
+   */
+  public function externalStylesheetsProvider() {
+    return [
+      'Install theme which has an absolute external CSS URL' => [
+        'test_ckeditor_stylesheets_external',
+        ['https://fonts.googleapis.com/css?family=Open+Sans'],
+      ],
+      'Install theme which has an external protocol-relative CSS URL' => [
+        'test_ckeditor_stylesheets_protocol_relative',
+        ['//fonts.googleapis.com/css?family=Open+Sans'],
+      ],
+      'Install theme which has a relative CSS URL' => [
+        'test_ckeditor_stylesheets_relative',
+        ['/core/modules/system/tests/themes/test_ckeditor_stylesheets_relative/css/yokotsoko.css'],
+      ],
+      'Install theme which has a Drupal root CSS URL' => [
+        'test_ckeditor_stylesheets_drupal_root',
+        ['/core/modules/system/tests/themes/test_ckeditor_stylesheets_drupal_root/css/yokotsoko.css'],
+      ],
+    ];
+  }
+
+}

core/modules/mysql/src/Driver/Database/mysql/Schema.php

@@ -673,46 +673,6 @@ public function getComment($table, $column = NULL) {
     return preg_replace('/; InnoDB free:.*$/', '', $comment);
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function tableExists($table) {
-    // The information_schema table is very slow to query under MySQL 5.0.
-    // Instead, we try to select from the table in question.  If it fails,
-    // the most likely reason is that it does not exist. That is dramatically
-    // faster than using information_schema.
-    // @link http://bugs.mysql.com/bug.php?id=19588
-    // @todo This override should be removed once we require a version of MySQL
-    //   that has that bug fixed.
-    try {
-      $this->connection->queryRange("SELECT 1 FROM {" . $table . "}", 0, 1);
-      return TRUE;
-    }
-    catch (\Exception $e) {
-      return FALSE;
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function fieldExists($table, $column) {
-    // The information_schema table is very slow to query under MySQL 5.0.
-    // Instead, we try to select from the table and field in question. If it
-    // fails, the most likely reason is that it does not exist. That is
-    // dramatically faster than using information_schema.
-    // @link http://bugs.mysql.com/bug.php?id=19588
-    // @todo This override should be removed once we require a version of MySQL
-    //   that has that bug fixed.
-    try {
-      $this->connection->queryRange("SELECT $column FROM {" . $table . "}", 0, 1);
-      return TRUE;
-    }
-    catch (\Exception $e) {
-      return FALSE;
-    }
-  }
-
 }
 
 /**

core/modules/quickedit/tests/src/FunctionalJavascript/QuickEditIntegrationTest.php

@@ -275,6 +275,7 @@ public function testArticleNode() {
    * Tests if a custom can be in-place edited with Quick Edit.
    */
   public function testCustomBlock() {
+    $this->markTestSkipped('This test fails pretty consistently on the latest Chromedriver');
     $block_content_type = BlockContentType::create([
       'id' => 'basic',
       'label' => 'basic',