ASP .Net MVC 3: Unit testing controller actions - asp.net-mvc

Question

I am quite new to Unit testing and Mock concepts. I am trying to figure out how to write a good test case for the basic out-of-the box user registration code below:
[HttpPost]
public ActionResult Register(RegisterModel model)
{
if (ModelState.IsValid)
{
// Attempt to register the user
MembershipCreateStatus createStatus;
Membership.CreateUser(model.UserName, model.Password, model.Email, null, null, true, null, out createStatus);
if (createStatus == MembershipCreateStatus.Success)
{
FormsAuthentication.SetAuthCookie(model.UserName, false /* createPersistentCookie */);
return RedirectToAction("Index", "Home");
}
else
{
ModelState.AddModelError("", ErrorCodeToString(createStatus));
}
}
// If we got this far, something failed, redisplay form
return View(model);
}
Below are some of the specific points where I need your opinion/help:
I do not necessarily want to create a new user in ASP .Net membership database.
Based on the model passed in, how do I really make sure that if the user was successfully registered or there were errors in the process.

Answer 1

You have a problem with your code. Your action depends on a static method: Membership.CreateUser. And as you know static methods are PITAs to unit test.
So you could weaken the coupling by introducing a level of abstraction:
public interface IMyService
{
MembershipCreateStatus CreateUser(string username, string password, string email);
}
and then have some implementation that would use the current Membership provider:
public class MyService: IMyService
{
public MembershipCreateStatus CreateUser(string username, string password, string email)
{
MembershipCreateStatus status;
Membership.CreateUser(username, password, email, null, null, true, null, out status);
return status;
}
}
and finally the controller:
public class AccountController : Controller
{
private readonly IMyService _service;
public AccountController(IMyService service)
{
_service = service;
}
[HttpPost]
public ActionResult Register(RegisterModel model)
{
if (ModelState.IsValid)
{
// Attempt to register the user
var status = _service.CreateUser(model.UserName, model.Password, model.Email);
if (status == MembershipCreateStatus.Success)
{
FormsAuthentication.SetAuthCookie(model.UserName, false /* createPersistentCookie */);
return RedirectToAction("Index", "Home");
}
else
{
ModelState.AddModelError("", ErrorCodeToString(createStatus));
}
}
// If we got this far, something failed, redisplay form
return View(model);
}
}
OK, now that we have weakened the coupling we could use a mocking framework to mock the service in the unit test and make it trivial.
For example using Rhino Mocks you could create the following tests to cover the 2 failure cases:
[TestMethod]
public void Register_Action_Should_Redisplay_View_If_Model_Is_Invalid()
{
// arrange
var sut = new AccountController(null);
var model = new RegisterModel();
sut.ModelState.AddModelError("", "invalid email");
// act
var actual = sut.Register(model);
// assert
Assert.IsInstanceOfType(actual, typeof(ViewResult));
var viewResult = actual as ViewResult;
Assert.AreEqual(model, viewResult.Model);
}
[TestMethod]
public void Register_Action_Should_Redisplay_View_And_Add_Model_Error_If_Creation_Fails()
{
// arrange
var service = MockRepository.GenerateStub<IMyService>();
service
.Stub(x => x.CreateUser(null, null, null))
.IgnoreArguments()
.Return(MembershipCreateStatus.InvalidEmail);
var sut = new AccountController(service);
var model = new RegisterModel();
// act
var actual = sut.Register(model);
// assert
Assert.IsInstanceOfType(actual, typeof(ViewResult));
var viewResult = actual as ViewResult;
Assert.AreEqual(model, viewResult.Model);
Assert.IsFalse(sut.ModelState.IsValid);
}
The final test is the success case. We still have an issue with it. The issue is the following line:
FormsAuthentication.SetAuthCookie(model.UserName, false);
What is this? It is a static method call. So we proceed the same way as we did with the membership provider to weaken the coupling of our controller and the forms authentication system.

Answer 2

To test this method you can follow two way
Inside the test class create a new class that inherits from Membership class and override the method CreateUser.
Use Moq to mock the class.
For the first case I will check if username is equal to "GoodUser" or "BadUser" and generate a MembershipCreateStatus.Success or a different status.
For the second I will setup two method that follow the same idea as in the other method. See this link for an example