TwigNamespaceTest.php

<?php

namespace Drupal\Tests\system\Kernel\Theme;

use Drupal\KernelTests\KernelTestBase;
use Twig\TemplateWrapper;

/**
 * Tests Twig namespaces.
 *
 * @group Theme
 */
class TwigNamespaceTest extends KernelTestBase {
    
    /**
     * Modules to enable.
     *
     * @var array
     */
    public static $modules = [
        'twig_theme_test',
        'twig_namespace_a',
        'twig_namespace_b',
        'node',
    ];
    
    /**
     * @var \Drupal\Core\Template\TwigEnvironment
     */
    protected $twig;
    protected function setUp() {
        parent::setUp();
        \Drupal::service('theme_installer')->install([
            'test_theme',
            'bartik',
        ]);
        $this->twig = \Drupal::service('twig');
    }
    
    /**
     * Checks to see if a value is a twig template.
     */
    public function assertTwigTemplate($value, $message = '') {
        $this->assertInstanceOf(TemplateWrapper::class, $value, $message);
    }
    
    /**
     * Tests template discovery using namespaces.
     */
    public function testTemplateDiscovery() {
        // Tests resolving namespaced templates in modules.
        $this->assertTwigTemplate($this->twig
            ->load('@node/node.html.twig'), 'Found node.html.twig in node module.');
        // Tests resolving namespaced templates in themes.
        $this->assertTwigTemplate($this->twig
            ->load('@bartik/page.html.twig'), 'Found page.html.twig in Bartik theme.');
    }
    
    /**
     * Tests template extension and includes using namespaces.
     */
    public function testTwigNamespaces() {
        // Test twig @extends and @include in template files.
        $test = [
            '#theme' => 'twig_namespace_test',
        ];
        $this->setRawContent(\Drupal::service('renderer')->renderRoot($test));
        $this->assertText('This line is from twig_namespace_a/templates/test.html.twig');
        $this->assertText('This line is from twig_namespace_b/templates/test.html.twig');
    }

}