TDD favours small methods so very well. If you're in the camp that says you should only write test against the required functionality it doesn't give you a huge benefit but if you're in the camp that writes tests for the implementation then it gives you much tighter control. Personally I fall somewhere between the two. Mostly I'm interested in the functionality but I'll also write tests for any parts of the implementation where I think it's crucial that it behaves in a certain way.