ViewsTemplateTest.php

<?php

namespace Drupal\Tests\views\Kernel;

use Drupal\views\Views;

/**
 * Tests the template retrieval of views.
 *
 * @group views
 *
 * @see \Drupal\views_test_data\Plugin\views\style\StyleTemplateTest
 */
class ViewsTemplateTest extends ViewsKernelTestBase {
    
    /**
     * {@inheritdoc}
     */
    public static $testViews = [
        'test_view_display_template',
    ];
    
    /**
     * Tests render functionality.
     */
    public function testTemplate() {
        // Make sure that the rendering just calls the preprocess function once.
        $output = Views::getView('test_view_display_template')->preview();
        $renderer = $this->container
            ->get('renderer');
        // Check that the renderd output uses the correct template file.
        $this->assertStringContainsString('This module defines its own display template.', (string) $renderer->renderRoot($output));
    }

}