Bolt\Twig\TwigExtension::stack PHP Method

    public function stack($types = [])
    {
        return $this->handlers['admin']->stack($types);
    }

 public function testStack()
 {
     $app = $this->getApp();
     $handlers = $this->getTwigHandlers($app);
     $handlers['admin'] = $this->getMockHandler('AdminHandler', 'stack');
     $twig = new TwigExtension($app, $handlers, true);
     $twig->stack();
 }