public function testRegisteringCustomProviderAtRuntime()
 {
     $request = Request::create('foo', 'GET');
     $route = new Route('GET', 'foo', []);
     $auth = new Shield($this->auth, $this->container, []);
     $auth->setRequest($request);
     $auth->setRoute($route);
     $auth->extend('custom', new CustomProviderStub());
     $auth->authenticate($request, $route);
     $this->assertInstanceOf('CustomProviderStub', $auth->getProviderUsed());
     $auth->extend('custom', function ($app) {
         $this->assertInstanceOf('Illuminate\\Container\\Container', $app);
         return new CustomProviderStub();
     });
     $auth->authenticate();
     $this->assertInstanceOf('CustomProviderStub', $auth->getProviderUsed());
 }