I've been doing a lot of playing with testing frameworks and working out what's the best to use for the different needs. There's two kinds of frameworks out there for .NET, mocking frameworks and isolation frameworks. There are different reasons for using the different framework types and I'm to try and explain which one is a good choice for what you're trying to do. What is mocking? Mocking is the concept of producing fake versions of the objects you want to operate with.