class FileFieldValidateTest

class FileFieldValidateTest extends WebDriverTestBase {
  use FileFieldCreationTrait;
  use TestFileCreationTrait;
  
  /**
   * {@inheritdoc}
   */
  protected static $modules = [
    'node',
    'file',
  ];
  
  /**
   * {@inheritdoc}
   */
  protected $defaultTheme = 'stark';
  
  /**
   * Tests the validation message is displayed only once for ajax uploads.
   */
  public function testAjaxValidationMessage() {
    $field_name = strtolower($this->randomMachineName());
    $this->drupalCreateContentType([
      'type' => 'article',
      'name' => 'Article',
    ]);
    $this->createFileField($field_name, 'node', 'article', [], [
      'file_extensions' => 'txt',
    ]);
    $this->drupalLogin($this->drupalCreateUser([
      'access content',
      'create article content',
    ]));
    $page = $this->getSession()
      ->getPage();
    $this->drupalGet('node/add/article');
    $image_file = current($this->getTestFiles('image'));
    $image_path = $this->container
      ->get('file_system')
      ->realpath($image_file->uri);
    $page->attachFileToField('files[' . $field_name . '_0]', $image_path);
    $elements = $page->waitFor(10, function () use ($page) {
      return $page->findAll('css', '.messages--error');
    });
    $this->assertCount(1, $elements, 'Ajax validation messages are displayed once.');
  }

}