AreaMessagesTest.php

<?php

namespace Drupal\Tests\views\Kernel\Handler;

use Drupal\Tests\views\Kernel\ViewsKernelTestBase;
use Drupal\views\Views;

/**
 * Tests the messages area handler.
 *
 * @group views
 * @see \Drupal\views\Plugin\views\area\Messages
 */
class AreaMessagesTest extends ViewsKernelTestBase {
    
    /**
     * Views used by this test.
     *
     * @var array
     */
    public static $testViews = [
        'test_area_messages',
    ];
    
    /**
     * Tests the messages area handler.
     */
    public function testMessageText() {
        \Drupal::messenger()->addStatus('My drupal set message.');
        $view = Views::getView('test_area_messages');
        $view->setDisplay('default');
        $this->executeView($view);
        $output = $view->render();
        $output = \Drupal::service('renderer')->renderRoot($output);
        $this->setRawContent($output);
        $this->assertText('My drupal set message.');
    }

}