How do i unit test this business logic?

Question

i have a method that does takes in a object and saves it to the database. But, before i save the object, i do the following...

(psuedo code)

if (IsAuthenticated)
{
   foo.UserId = AuthenticatedUser.Id;
}
else
{
   foo.AnonEmail = "Jon@World-Domination";
   foo.AnonName = "Jon Skeet";
}

try
{
    _fooService.Save(foo);
}
catch
{
    // Some view, with error stuff now added to 
    return View(...); ViewData.ModelState.
}

// all good, redirect to the proper next view.
return RedirectToAction(...);

That code works fine, but i'm not sure how to write the two unit tests for a success. a) User is authenticated with valid data b) User is not authentiated with valid data.

The reason why i'm not sure what to do is, is that both scenario return the same RedirectToAction(..) view object. So i can successfully test that .. but it doesn't tell me if the object saved contains the authenticated user id or the anon info. It's like i want the first unit test to say

• moq up an authenticated user
• call method
• test if result is RedirectToActionView
• test if the foo object that was persisted contains the moq'd user id.

thoughts?

Update

The common suggestion is that i mock the fooService. I'm currently using Dependency Injection and Moq, so could somone show me how i would use Moq? I'm not sure how the DI is important here, though ???

Answer 1

I would mock up the _fooService object, and test what it receives as part of your test. That way your surrounding code remains the same and is untouched, and by checking what _fooService receives, you can assert whether the behaviour is as expected. The return object is not of interest in this case.

How do you mock your _fooService ? You can either implement your own 'test' version (adhering to the same interface as the real world version), or using a mocking framework. Whichever approach you use, your code above needs to be configured with a given implementation of the _fooService (usually on construction - see dependency injection for more info on how this may work)