Symfony\Bridge\Twig\Extension\FormExtension::initRuntime PHP Method

    public function initRuntime(\Twig_Environment $environment)
    {
        if ($this->renderer instanceof TwigRendererInterface) {
            $this->renderer->setEnvironment($environment);
        } elseif (null !== $this->renderer) {
            $this->renderer[2] = $environment;
        }
    }

 /**
  * {@inheritdoc}
  */
 public function setUp()
 {
     parent::setUp();
     if (!in_array($this->type, array('form', 'filter'))) {
         throw new \Exception('Please override $this->type in your test class specifying template to use (either form or filter)');
     }
     $rendererEngine = new TwigRendererEngine(array($this->type . '_admin_fields.html.twig'));
     $csrfManagerClass = interface_exists('Symfony\\Component\\Security\\Csrf\\CsrfTokenManagerInterface') ? 'Symfony\\Component\\Security\\Csrf\\CsrfTokenManagerInterface' : 'Symfony\\Component\\Form\\Extension\\Csrf\\CsrfProvider\\CsrfProviderInterface';
     $renderer = new TwigRenderer($rendererEngine, $this->getMock($csrfManagerClass));
     $this->extension = new FormExtension($renderer);
     $twigPaths = array(__DIR__ . '/../../../Resources/views/Form');
     //this is ugly workaround for different build strategies and, possibly,
     //different TwigBridge installation directories
     if (is_dir(__DIR__ . '/../../../vendor/symfony/twig-bridge/Resources/views/Form')) {
         $twigPaths[] = __DIR__ . '/../../../vendor/symfony/twig-bridge/Resources/views/Form';
     } elseif (is_dir(__DIR__ . '/../../../vendor/symfony/symfony/src/Symfony/Bridge/Twig/Resources/views/Form')) {
         $twigPaths[] = __DIR__ . '/../../../vendor/symfony/symfony/src/Symfony/Bridge/Twig/Resources/views/Form';
     } else {
         $twigPaths[] = __DIR__ . '/../../../../../symfony/symfony/src/Symfony/Bridge/Twig/Resources/views/Form';
     }
     $loader = new StubFilesystemLoader($twigPaths);
     $this->environment = new \Twig_Environment($loader, array('strict_variables' => true));
     $this->environment->addGlobal('sonata_admin', $this->getSonataAdmin());
     $this->environment->addExtension(new TranslationExtension(new StubTranslator()));
     $this->environment->addExtension($this->extension);
     $this->extension->initRuntime($this->environment);
 }