I've used AutoMapper in my controller for mapping my Model objects to my ViewModel objects. A IMappingEngine object is injected in my controllers by Unity and the Mapping configuration is done in the global.asax.
In my controller's unit tests, how should I mock the IMappingEngine passed as parameter in the constructor ?
Do I have to setup all the mapping configuration again in the unit test project ?
If you are abstracting AutoMapper through the use of an interface the point of this is so that you do NOT have to use AutoMapper in your unit test. It is a unit test so you are testing just the code in the controller action. All you need to do is use a mocking framework like RhinoMocks or Moq and mock the behaviour you need for your test. With RhinoMocks you would have something like this:
var mapper= MockRepository.GenerateStub<IMappingEngine>();
and then use mapper.Stub to add the behaviour you need.
Why are you injecting AutoMapper in the first place?
What are your tests suppose to test since the output of your controller (ViewModels) is dependent on the mappings?
I suspect you have a bit too much abstractions in your code. There is nothing wrong with using the AutoMapper directly.
