Issue #3269140 by longwave: Remove deprecated config.storage.staging service

  config.storage.sync:

    class: Drupal\Core\Config\FileStorage

    factory: Drupal\Core\Config\FileStorageFactory::getSync

  config.storage.staging:

    alias: config.storage.sync

    deprecated: The "%alias_id%" service is deprecated in drupal:8.0.0 and is removed from drupal:10.0.0. Use the "config.storage.sync" service instead. See https://www.drupal.org/node/2574957

  config.storage.snapshot:

    class: Drupal\Core\Config\DatabaseStorage

    arguments: ['@database', config_snapshot]

<?php

namespace Drupal\KernelTests\Core\Config;

use Drupal\Core\Config\FileStorage;

use Drupal\KernelTests\KernelTestBase;

/**

 * Tests that the service "config.storage.staging" has been deprecated.

 *

 * @group Test

 * @group legacy

 */

class ConfigStorageStagingTest extends KernelTestBase {

  /**

   * Tests deprecation of the "config.storage.staging" service.

   */

  public function testConfigStorageStagingDeprecation() {

    $this->expectDeprecation('The "config.storage.staging" service is deprecated in drupal:8.0.0 and is removed from drupal:10.0.0. Use the "config.storage.sync" service instead. See https://www.drupal.org/node/2574957');

    // @phpstan-ignore-next-line

    $storage_staging = \Drupal::service('config.storage.staging');

    // Ensure at least one assertion.

    $this->assertInstanceOf(FileStorage::class, $storage_staging);

  }

}