Symfony unit test Security (ACL)

I'd like to check a method with access control, e.g. a method is only granted with a specific role. Therefore, I know two ways in Symfony:

1. @Security annotation above the method OR
2. Calling authorization_checker explizit within my method

When it comes to unit tests (for my case phpspec, but I think phpunit behaviour is the almost the same in that case), I would like to test that only anonymous users should be able to call a method. With number 2. , it's working fine. Here my setup:

RegistrationHandlerSpec:

class RegistrationHandlerSpec extends ObjectBehavior
{     
   function let(Container $container, AuthorizationCheckerInterface $auth) {
     $container->get('security.authorization_checker')->willReturn($auth);
     $this->setContainer($container);
   }

   function it_should_block_authenticated_users(AuthorizationCheckerInterface $auth)
   {
     $auth->isGranted("ROLE_USER")->willReturn(true);
     $this->shouldThrow('Symfony\Component\Security\Core\Exception\AccessDeniedException')->during('process', array());
   }  
}

And within the RegistrationHandler, I have the following method:

class RegistrationHandler
{
  public function process()
  {
     $authorizationChecker = $this->get('security.authorization_checker');
     if ($authorizationChecker->isGranted('ROLE_USER')) {
         throw new AccessDeniedException();
     }
     // ...
  }
}

Well, this approach is working fine - BUT normally, I would prefer using 1. with Security annotation (Sensio FrameworkExtraBundle), and therefore, it's not working / I don't know why no Exception gets triggered when it's written as an annotation:

/**
 * @Security("!has_role('ROLE_USER')")
 */
public function process()
{
   // ...
}

Does anyone know how to get this example to work by using the first approach with @Security annotation, which is way more readable and best practice recommended of symfony?