Using Moq with NUnit

Aug 19, 2009 archive

As I continue to work with unit tests, I have noticed that some of my development patterns have started to change…for the better.

In the NerdDinner tutorial, I use to create test classes with private members that are initialized in a TextFixtureSetUp method. If we consider that I am to test a DinnerController with a mock repository, the approach would be as such:

private DinnerController controller;
private Mock<IDinnerRepository> repository;

[TestFixtureSetUp]
public void Init()
{
   repository = MockClasses.GetMockDinnerRepository();
   controller = new DinnerController(repository.Object);
}

However, consider the following tests:

[Test]
public void Details_ShouldDisplayDetailsForValidDinner()
{
   ViewResult result = (ViewResult)controller.Details(1);
   Dinner data = (Dinner)result.ViewData.Model;

   Assert.That(result.ViewName, Is.EqualTo("Details"));
   Assert.That(data.IsValid, Is.EqualTo(true));

   repository.Verify(x => x.Get(1), Times.Once());
}

[Test]
public void Edit_ShouldDisplayEditForValidDinner()
{
   ViewResult result = (ViewResult)controller.Edit(1);
   Dinner data = (Dinner)result.ViewData.Model;

   Assert.That(result.ViewName, Is.EqualTo("Edit"));
   Assert.That(data.IsValid, Is.EqualTo(true));

   repository.Verify(x => x.Get(1), Times.Once());
}

Since the two test cases use the same object instances, their verifications will not work as expected. The repository’s Get function will be called twice, since both test cases call it.

The solution is to replace [TextFixtureSetUp] with [SetUp]. The former is called once, prior to all tests, which the latter is called before each test case.