install(['classy']); $this->config('system.theme')->set('default', 'classy')->save(); \Drupal::messenger()->addError('An error occurred'); \Drupal::messenger()->addStatus('But then something nice happened'); $messages = [ '#type' => 'status_messages', ]; $this->render($messages); $this->assertRaw('messages messages--error'); $this->assertRaw('messages messages--status'); // Tests display of only one type of messages. \Drupal::messenger()->addError('An error occurred'); $messages = [ '#type' => 'status_messages', '#display' => 'error', ]; $this->render($messages); $this->assertRaw('messages messages--error'); } }