Recently, I read Growing Object-Oriented Software, Guided by Tests by Steve Freeman and Nat Pryce. Amongst excellent discussions of other TDD topics, it sheds a lot of light on good ways to use mock objects.
Personally, I can remember reading Martin Fowler's Mocks Aren't Stubs quite a while ago and concluding that I'd be a "classicist."
Some time later, I started working with mocks as a way to isolate unit tests from "slow" dependencies, such as databases, trying to make them run more quickly. I didn't have much success, though, because I was still writing my tests in a classicist style.
This book helped open my eyes to how the "mockist" style really works, and why it can be a good thing. I absolutely recommend it to any programmer who is doing TDD (or writing unit tests), but who still feels like when it comes to being a mockist, they just don't get it.
I also think a great complement to the book is the video of J. B. Rainsberger's presentation Integration Tests Are A Scam.
As a note on how to read the book, I got a bit bogged down in the middle section, with the worked example. I ended up skipping to the final section and came back to the middle after. Reading it like that worked just fine. I also think it could be interesting to alternate chapters of the middle section with those of the final section.
