RhinoMocks

I am digging deeper into fakes using RhinoMocks.  I set up a test project that uses a Mock of an InterfaceKit and then sets up some expected return values.  For example:

        [TestInitialize()]
        public void InterfaceKitTestInitialize()
        {
            MockRepository mockRepository = new MockRepository();
            interfaceKit = mockRepository.StrictMock<IInterfaceKit>();
            Expect.Call(interfaceKit.Address).Return("ValidAddress");
            mockRepository.ReplayAll();
        }

And a subsequent test:

        [TestMethod()]

        public void InterfaceKitAddress_ReturnsValidValue()

        {

            string expected = "ValidAddress";

            string actual = interfaceKit.Address;

            Assert.AreEqual(expected, actual);

        }

So far so good – it comes back green.  But then I thought “So what?”  All I am really doing is testing the Mock API.  Unless there is some business logic in the getter, then mocking properties are useless.  I guess you would use a mock over a stub because you can control the number of properties that you need to test – you don’t have to set up a whole  object graph if you just want to test 1 property.

I also noticed that I could use this syntax instead of using Expect.Call:

SetupResult.For(interfaceKit.Address).Return("ValidAddress");

 I then tried to venture on to mock a method.  I attempted to add a new line to my initialization method like this:

Expect.Call(interfaceKit.open());

However, I am getting some errors:

I then realized that I had a syntax error for parameter-less methods:

Expect.Call(interfaceKit.open).Return(null);

 This works – but I am not testing anything.  So I thought a bit more – why would you even mock a method that does not return a value and does not take a parameter?  Unless there is another dependency that the method needs to run (for example, setting a property of the object before calling the method) and the only way you know if it ran was if you got an exception, there is no point.

Expect.Call(interfaceKit.open).Throw(new PhidgetException(ErrorType.PHIDGET_ERR_CLOSED));

I guess this is what they mean when they say that mocking and unit testing forces you to make a better API.  The Phidget kit does this (open then wait for the event).  I then made a test to check the exception

        [TestMethod()]

        [ExpectedException(typeof(PhidgetException))]

        public void InterfaceKitAttachedTest_ThrowsError()

        {

            interfaceKit.open();

            Assert.Fail("Should never get here");

        }

 and the test passed.  If I wanted to test the value of the ErrorType, I would put it into a try..catch block in the test and inspect the PhidgetException.ErrorType property and remove the ExpectedException attribute.