--- /dev/null
+<?php
+
+namespace Drupal\Tests\system\Functional\Theme;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Tests the multi theme engine support.
+ *
+ * @group Theme
+ */
+class EngineNyanCatTest extends BrowserTestBase {
+
+ /**
+ * Modules to enable.
+ *
+ * @var array
+ */
+ public static $modules = ['theme_test'];
+
+ protected function setUp() {
+ parent::setUp();
+ \Drupal::service('theme_handler')->install(['test_theme_nyan_cat_engine']);
+ }
+
+ /**
+ * Ensures a theme's template is overridable based on the 'template' filename.
+ */
+ public function testTemplateOverride() {
+ $this->config('system.theme')
+ ->set('default', 'test_theme_nyan_cat_engine')
+ ->save();
+ $this->drupalGet('theme-test/template-test');
+ $this->assertText('Success: Template overridden with Nyan Cat theme. All of them', 'Template overridden by Nyan Cat file.');
+ }
+
+}