assertSession();
// Check that anonymous users can not preview files.
$this->drupalGet('/webform/test_element_managed_file_prev/test');
$assert_session->responseContains('webform_image_file.gif');
$assert_session->responseContains('webform_audio_file.mp3');
$assert_session->responseContains('webform_video_file.mp4');
$assert_session->responseContains('webform_document_file.txt');
// Login admin user.
$this->drupalLogin($this->rootUser);
// Check that authenticated users can preview files.
$this->drupalGet('/webform/test_element_managed_file_prev/test');
$assert_session->responseContains(' 