Using the Ninject.MockingKernel is cool…

Ok, so what is so cool about the Ninject.MockingKernel?  Here are some of the biggest benefits that I have found so far…

• It saves me from having to worry about test setup code, and I can focus more on arranging the test
• The mocking kernel will manage stub and mock lifetimes for me, so I simply request a stub or mock for the test in question
• It seems like I am less concerned with the state of the “Mocking Framework” (normally Rhino Mocks) because the mocking kernel is managing this for me

So here is a quick sample of how I am using the Ninject.MockingKernel and more specifically the RhinoMocksMockingKernel…

Here is the test setup…

[SetUp]
public void Setup()
{
    container = new RhinoMocksMockingKernel();
    controller = container.Get<UsersController>();
    customerRepository = container.Get<ICustomerRepository>();
}

Notice in the setup that I didnt need to execute any calls to MockRepository.GenerateStub<T>() or MockRepository.GenerateMock<T>().  Also notice that I use the auto mocking container to create an instance of my controller.  In my setup I can initalize a member level variable and use this variable in each test OR in each test I can call Get<T>() on the container.  Either way, the stubs and mocks that are returned from the auto mocking container can be used as stubs or mocks and I can make assertions on those mocks and stubs.

Here are the two tests that exercise the “Delete” method of my “UsersController”…

[TestCase(123, 456, "joe")]
[TestCase(456, 789, "jim")]
public void Delete_Updates_CustomerStatistics(int customerId, int userId, string userName)
{
    var testCustomer = new Customer { Id = customerId };
    container.Get<ICustomerRepository>().Stub(it => it.FindCustomerForUser(userId)).Return(testCustomer);
    container.Get<ICustomerRepository>().Expect(it => it.UpdateCustomerStatistics(customerId)).Return(1);

    controller.Delete(userId, userName);

    container.Get<ICustomerRepository>().VerifyAllExpectations();
}

[TestCase(123)]
[TestCase(456)]
public void Delete_Loads_RelatedCustomer(int userId)
{
    var testCustomer = new Customer { Id = 123 };
    container.Get<ICustomerRepository>().Expect(it => it.FindCustomerForUser(userId)).Return(testCustomer);

    controller.Delete(userId, "joe");

    container.Get<ICustomerRepository>().VerifyAllExpectations();
}

And here is the code under test…

[HttpPost]
public ActionResult Delete(int userId, string userName)
{
    var customer = customerRepository.FindCustomerForUser(userId);

    userRepository.DeleteUser(userId, userName);

    customerRepository.UpdateCustomerStatistics(customer.Id);

    return new JsonResult
    {
        Data = new Ack
        {
            Status = AckStatus.Success,
            Message = "User deleted"
        }
    };
}

 Another interesting note, is that the code under test actually has a dependency on the “userRepository” and you should have noticed that nowhere in my test or my test setup did I create a mock or stub for IUserRepository.

Here is the constructor for my UsersController:

public UsersController(IUsersRepository userRepository, IMembershipService membershipService, IRolesService rolesService, ICustomerRepository customerRepository)
{
    this.rolesService = rolesService;
    this.membershipService = membershipService;
    this.userRepository = userRepository;
    this.customerRepository = customerRepository;
}

So, if you are looking for some new tools to add to your testing tool belt, consider taking the Ninject.MockingKernel for a test drive…

If you are using VS.NET 2010 you can download the package via NuGet or you can get the code from here.