trait StubTestTrait in Drupal 8

trait StubTestTrait {

  /**
   * Test that creating a stub of the given entity type results in a valid
   * entity.
   *
   * @param string $entity_type_id
   *   The entity type we are stubbing.
   */
  protected function performStubTest($entity_type_id) {
    $entity_id = $this
      ->createEntityStub($entity_type_id);
    $this
      ->assertNotEmpty($entity_id, 'Stub successfully created');

    // When validateStub fails, it will return an array with the violations.
    $this
      ->assertEmpty($this
      ->validateStub($entity_type_id, $entity_id));
  }

  /**
   * Create a stub of the given entity type.
   *
   * @param string $entity_type_id
   *   The entity type we are stubbing.
   *
   * @return int
   *   ID of the created entity.
   */
  protected function createEntityStub($entity_type_id) {

    // Create a dummy migration to pass to the destination plugin.
    $definition = [
      'migration_tags' => [
        'Stub test',
      ],
      'source' => [
        'plugin' => 'empty',
      ],
      'process' => [],
      'destination' => [
        'plugin' => 'entity:' . $entity_type_id,
      ],
    ];
    $migration = \Drupal::service('plugin.manager.migration')
      ->createStubMigration($definition);
    $destination_plugin = $migration
      ->getDestinationPlugin(TRUE);
    $stub_row = new Row([], [], TRUE);
    $destination_ids = $destination_plugin
      ->import($stub_row);
    return reset($destination_ids);
  }

  /**
   * Perform validation on a stub entity.
   *
   * @param string $entity_type_id
   *   The entity type we are stubbing.
   * @param string $entity_id
   *   ID of the stubbed entity to validate.
   *
   * @return \Drupal\Core\Entity\EntityConstraintViolationListInterface
   *   List of constraint violations identified.
   */
  protected function validateStub($entity_type_id, $entity_id) {
    $controller = \Drupal::entityTypeManager()
      ->getStorage($entity_type_id);

    /** @var \Drupal\Core\Entity\ContentEntityInterface $stub_entity */
    $stub_entity = $controller
      ->load($entity_id);
    return $stub_entity
      ->validate();
  }

}