How can I unit test my ASP.NET MVC controller that uses FormsAuthentication?

Question

I'm working with a ASP.NET MVC solution in a test driven manner and I want to login a user to my application using forms authentication. The code I would like to end up with in the controller looks something like this:

FormsAuthentication.SetAuthCookie(userName, false); 

My question is how do I write a test to justify this code?

Is there a way to check that the SetAuthCookie method was called with the correct parameters?

Is there any way of injecting a fake/mock FormsAuthentication?

Answer 1

I would start by writing an interface and a wrapper class that will encapsulate this logic and then use the interface in my controller:

public interface IAuth  {     void DoAuth(string userName, bool remember); }  public class FormsAuthWrapper : IAuth  {     public void DoAuth(string userName, bool remember)      {         FormsAuthentication.SetAuthCookie(userName, remember);     } }  public class MyController : Controller  {     private readonly IAuth _auth;      public MyController(IAuth auth)      {         _auth = auth;     }  } 

Now IAuth could be easily mocked in a unit test and verify that the controller calls the expected methods on it. I would NOT unit test the FormsAuthWrapper class because it just delegates the call to the FormsAuthentication which does what it is supposed to do (Microsoft guarantee :-)).