Issue #3415060 by Spokje, smustgrave: Convert AlterTest into a Kernel test

<?php

namespace Drupal\Tests\system\Functional\Common;

namespace Drupal\Tests\system\Kernel\Common;

use Drupal\Tests\BrowserTestBase;

use Drupal\KernelTests\KernelTestBase;

/**

 * Tests alteration of arguments passed to \Drupal::moduleHandler->alter().

 *

 * @group Common

 */

class AlterTest extends BrowserTestBase {

  /**

   * Modules to enable.

   *

   * @var array

   */

  protected static $modules = ['block', 'common_test'];

class AlterTest extends KernelTestBase {

  /**

   * {@inheritdoc}

   */

  protected $defaultTheme = 'stark';

  protected static $modules = [

    'block',

    'common_test',

    'system',

  ];

  /**

   * Tests if the theme has been altered.

   */

  public function testDrupalAlter() {

  public function testDrupalAlter(): void {

    // This test depends on Olivero, so make sure that it is always the current

    // active theme.

    \Drupal::service('theme_installer')->install(['olivero']);

    // Verify alteration of multiple arguments.

    $array_copy = $array;

    $array_expected = ['foo' => 'Drupal theme'];

    $entity_copy = clone $entity;

    $entity_expected = clone $entity;

    $entity_expected->foo = 'Drupal theme';