Issue #3279850 by alexpott, dww, lauriii: Theme post updates are not...

  public function onConfigSave(ConfigCrudEvent $event) {

    $config = $event->getConfig();

    if ($config->getName() === 'core.extension') {

      // Build the old extension configuration list from configuration rather

      // than using $this->enabledExtensions. This ensures that if the

      // UpdateRegistry is constructed after _drupal_maintenance_theme() has

      // added a theme to the theme handler it will not be considered as already

      // installed.

      $old_extension_list = array_keys($config->getOriginal('module') ?? []);

      $new_extension_list = array_keys($config->get('module'));

      if ($this->includeThemes()) {

        $new_extension_list = array_merge($new_extension_list, array_keys($config->get('theme')));

        $old_extension_list = array_merge($old_extension_list, array_keys($config->getOriginal('theme') ?? []));

      }

      // The list of extensions installed or uninstalled. In regular operation

      // only one of the lists will have a single value. This is because Drupal

      // can only install one extension at a time.

      $uninstalled_extensions = array_diff($this->enabledExtensions, $new_extension_list);

      $installed_extensions = array_diff($new_extension_list, $this->enabledExtensions);

      $uninstalled_extensions = array_diff($old_extension_list, $new_extension_list);

      $installed_extensions = array_diff($new_extension_list, $old_extension_list);

      // Set the list of enabled extensions correctly so update function

      // discovery works as expected.

<?php

namespace Drupal\Tests\system\Functional\Theme;

use Drupal\Core\Serialization\Yaml;

use Drupal\Tests\BrowserTestBase;

use Drupal\Tests\RequirementsPageTrait;

/**

 * Ensures theme update functions are registered for maintenance themes.

 *

 * @group Theme

 */

class MaintenanceThemeUpdateRegistryTest extends BrowserTestBase {

  use RequirementsPageTrait;

  /**

   * {@inheritdoc}

   */

  protected $profile = 'theme_test_profile';

  /**

   * {@inheritdoc}

   */

  protected function prepareSettings() {

    parent::prepareSettings();

    $this->writeSettings([

      'settings' => [

        'maintenance_theme' => (object) [

          'value' => 'test_theme_updates',

          'required' => TRUE,

        ],

      ],

    ]);

  }

  /**

   * {@inheritdoc}

   */

  protected function prepareEnvironment() {

    parent::prepareEnvironment();

    $info = [

      'type' => 'profile',

      'core_version_requirement' => '*',

      'name' => 'Theme test profile',

      'themes' => [

        'test_theme_updates',

      ],

    ];

    // Create an install profile that uses the test theme.

    $path = $this->siteDirectory . '/profiles/theme_test_profile';

    mkdir($path, 0777, TRUE);

    file_put_contents("$path/theme_test_profile.info.yml", Yaml::encode($info));

    // Create a system.theme.yml file for the profile so the test theme is used.

    $path = $this->siteDirectory . '/profiles/theme_test_profile/config/install';

    mkdir($path, 0777, TRUE);

    $theme_config = Yaml::decode(file_get_contents(\Drupal::moduleHandler()->getModule('system')->getPath() . '/config/install/system.theme.yml'));

    $theme_config['default'] = 'test_theme_updates';

    file_put_contents("$path/system.theme.yml", Yaml::encode($theme_config));

  }

  /**

   * Tests that after installing the profile there are no outstanding updates.

   */

  public function testMaintenanceThemeUpdateRegistration() {

    $this->drupalLogin($this->rootUser);

    $this->drupalGet('update.php/selection');

    $this->updateRequirementsProblem();

    $this->drupalGet('update.php/selection');

    $this->assertSession()->pageTextContains('No pending updates.');

  }

}

name: Test Theme Updates

type: theme

description: A theme that has a post update.

version: VERSION

base theme: false

<?php

/**

 * @file

 * Update functions for the theme.

 */

/**

 * Tests post updates for themes.

 */

function test_theme_updates_post_update_test(&$sandbox = NULL) {

  // Do nothing.

}