ASP.NET MVC - Unit testing overkill? (TDD)

So I'm starting to catch the TDD bug but I'm wondering if I'm really doing it right... I seem to be writing A LOT of tests.

The more tests the better, sure, but I've got a feeling that I'm over doing it. And to be honest, I don't know how long I can keep up writing these simple repetitive tests.

For instance, these are the LogOn actions from my AccountController:

public ActionResult LogOn(string returnUrl)
{
    if (string.IsNullOrEmpty(returnUrl))
        returnUrl = "/";

    var viewModel = new LogOnForm()
    {
        ReturnUrl = returnUrl
    };

    return View("LogOn", viewModel);
}

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult LogOn(LogOnForm logOnForm)
{
    try
    {
        if (ModelState.IsValid)
        {
            AccountService.LogOnValidate(logOnForm);

            FormsAuth.SignIn(logOnForm.Email, logOnForm.RememberMe);

            return Redirect(logOnForm.ReturnUrl);
        }
    }
    catch (DomainServiceException ex)
    {
        ex.BindToModelState(ModelState);
    }
    catch
    {
        ModelState.AddModelError("*", "There was server error trying to log on, try again. If your problem persists, please contact us.");
    }

    return View("LogOn", logOnForm);
}

Pretty self explanatory.

I then have the following suite of tests

public void LogOn_Default_ReturnsLogOnView()
public void LogOn_Default_SetsViewDataModel()
public void LogOn_ReturnUrlPassedIn_ViewDataReturnUrlSet()
public void LogOn_ReturnUrlNotPassedIn_ViewDataReturnUrDefaults()
public void LogOnPost_InvalidBinding_ReturnsLogOnViewWithInvalidModelState()
public void LogOnPost_InvalidBinding_DoesntCallAccountServiceLogOnValidate()
public void LogOnPost_ValidBinding_CallsAccountServiceLogOnValidate()
public void LogOnPost_ValidBindingButAccountServiceThrows_ReturnsLogOnViewWithInvalidModelState()
public void LogOnPost_ValidBindingButAccountServiceThrows_DoesntCallFormsAuthServiceSignIn()
public void LogOnPost_ValidBindingAndValidModelButFormsAuthThrows_ReturnsLogOnViewWithInvalidModelState()
public void LogOnPost_ValidBindingAndValidModel_CallsFormsAuthServiceSignIn()
public void LogOnPost_ValidBindingAndValidModel_RedirectsToReturnUrl()

Is that over kill? I haven't even shown the services tests!

Which ones (if any) can I cull?

TIA,
Charles

Solution

It all depends on how much coverage you need / want and how much dependability is an issue.

Here are the questions you should ask yourself:

Does this unit test help implement a feature / code change that I don't already have?
Will this unit test help regression test/debug this unit if I make changes later?
Is the code to satisfy this unit test non-trivial or does it deserve a unit test?

Regarding the 3rd one, I remember when I started writing unit tests (I know, not the same thing as TDD) I would have tests that would go like:

string expected, actual;
TypeUnderTest target = new TypeUnderTest();
target.PropertyToTest = expected;
actual = target.PropertyToTest;
Assert.AreEqual<string>(expected, actual);

I could have done something more productive with my time like choose a better wallpaper for my desktop.

I recommend this article by ASP.net MVC book author Sanderson:

http://blog.codeville.net/2009/08/24/writing-great-unit-tests-best-and-worst-practises/