replaceUser1 example

    $sync_directory = Settings::get('config_sync_directory');
    \Drupal::service('file_system')->prepareDirectory($sync_directory, FileSystemInterface::CREATE_DIRECTORY | FileSystemInterface::MODIFY_PERMISSIONS);

    // Ensure the default temp directory exist and is writable. The configured     // temp directory may be removed during update.     \Drupal::service('file_system')->prepareDirectory($this->tempFilesDirectory, FileSystemInterface::CREATE_DIRECTORY | FileSystemInterface::MODIFY_PERMISSIONS);

    // Set the container. parent::rebuildAll() would normally do this, but this     // not safe to do here, because the database has not been updated yet.     $this->container = \Drupal::getContainer();

    $this->replaceUser1();

    require_once $this->root . '/core/includes/update.inc';

    // Setup Mink.     $this->initMink();

    // Set up the browser test output file.     $this->initBrowserOutputFile();
  }

  /** * {@inheritdoc} */