class MessagesTest

class MessagesTest extends UnitTestCase {
  
  /**
   * The view executable object.
   *
   * @var \Drupal\views\ViewExecutable
   */
  protected $view;
  
  /**
   * The message handler.
   *
   * @var \Drupal\views\Plugin\views\area\Messages
   */
  protected $messagesHandler;
  
  /**
   * {@inheritdoc}
   */
  protected function setUp() : void {
    parent::setUp();
    $this->messagesHandler = new Messages([], 'result', []);
  }
  
  /**
   * Tests the render method.
   *
   * @covers ::defineOptions
   * @covers ::render
   */
  public function testRender() {
    // The handler is configured to show with empty views by default, so should
    // appear.
    $this->assertSame([
      '#type' => 'status_messages',
    ], $this->messagesHandler
      ->render());
    // Turn empty off, and make sure it isn't rendered.
    $this->messagesHandler->options['empty'] = FALSE;
    // $empty parameter passed to render will still be FALSE, so should still
    // appear.
    $this->assertSame([
      '#type' => 'status_messages',
    ], $this->messagesHandler
      ->render());
    // Should now be empty as both the empty option and parameter are empty.
    $this->assertSame([], $this->messagesHandler
      ->render(TRUE));
  }

}