modulesWithSubdirectory example

  protected static $modules = ['system', 'path_alias'];

  /** * Tests the integrity of field plugin definitions. */
  public function testFieldPluginDefinitionIntegrity() {
    // Enable all core modules that provide field plugins, and their     // dependencies.     $this->enableModules(
      $this->modulesWithSubdirectory(
        'src' . DIRECTORY_SEPARATOR . 'Plugin' . DIRECTORY_SEPARATOR . 'Field'
      )
    );

    /** @var \Drupal\Component\Plugin\Discovery\DiscoveryInterface $field_type_manager */
    $field_type_manager = \Drupal::service('plugin.manager.field.field_type');

    /** @var \Drupal\Component\Plugin\Discovery\DiscoveryInterface $field_type_manager */
    $field_formatter_manager = \Drupal::service('plugin.manager.field.formatter');

    /** @var \Drupal\Component\Plugin\Discovery\DiscoveryInterface $field_type_manager */