class DrupalFlushAllCachesInInstallerTest

class DrupalFlushAllCachesInInstallerTest extends BrowserTestBase {
  
  /**
   * {@inheritdoc}
   */
  protected $defaultTheme = 'stark';
  
  /**
   * {@inheritdoc}
   */
  protected $profile = 'cache_flush_test';
  
  /**
   * {@inheritdoc}
   */
  protected function prepareEnvironment() {
    parent::prepareEnvironment();
    $info = [
      'type' => 'profile',
      'core_version_requirement' => '*',
      'name' => 'Cache flush test',
      'install' => [
        'language',
      ],
    ];
    // File API functions are not available yet.
    $path = $this->siteDirectory . '/profiles/cache_flush_test';
    mkdir($path, 0777, TRUE);
    file_put_contents("{$path}/cache_flush_test.info.yml", Yaml::encode($info));
    $php_code = <<<EOF
    <?php
    function cache_flush_test_install() {
      // Note it is bad practice to call this method during hook_install() as it
      // results in an additional expensive container rebuild.
      drupal_flush_all_caches();
      // Ensure services are available after calling drupal_flush_all_caches().
      \\Drupal::state()->set('cache_flush_test', \\Drupal::hasService('language_negotiator'));
    }
    EOF;
    file_put_contents("{$path}/cache_flush_test.install", $php_code);
  }
  
  /**
   * Confirms that the installation succeeded.
   */
  public function testInstalled() {
    $this->assertTrue(\Drupal::state()->get('cache_flush_test'));
  }

}