Moq .NET Mocking Library
Moq offers the following features:
Moq is open source and eager for more contributors. Along with the source, the binaries and a getting started guide are hosted on Google Code.
Strong-typed: no strings for expectations, no object-typed return values or constraints Unsurpassed VS intellisense integration: everything supports full VS intellisense, from setting expectations, to specifying method call arguments, return values, etc. No Record/Reply idioms to learn. Just construct your mock, set your expectations, use it and optionally verify them VERY low learning curve as a consequence of the previous three points. For the most part, you don't even need to ever read the documentation. Granular control over mock behavior with a simple MockBehavior enumeration (no need to learn what's the theoretical difference between a mock, a stub, a fake, a dynamic mock, etc.) Mock both interfaces and classes Override expectations: can set default expectations in a fixture setup, and override as needed on tests Pass constructor arguments for mocked classes Intercept and raise events on mocks
Daniel Cazzulino, Moq's active maintainer, has a series of posts that provide his reasoning for creating Moq and several good examples of how to use Moq effectively.