Ralf has a nice tidbit about how .NET 2.0 Partial Classes can help you with writing unit tests for methods on classes that are otherwise harder to get to. It's a nice trick to add to the trick bag, though I'd argue that if you were doing Test-Driven-Development in the first place, you'd have a testable design out-of-the-box , and you wouldn't need to come up with clever hacks such as these. Having said that, sometimes you just don't have a choice and you need to write tests for legacy code (a.k.a...