"Continuous Testing with Ruby" is now available as a beta book on pragprog.com! This is the first beta, so there's still more to do, but Rod and I are very happy to have it out there so we can get some feedback.
Continuous Testing starts with a simple idea: Run your tests all the time. I think this book does a great job of communicating all the incremental improvements to that idea that Rod and I have come up with over the last few years. From using CT as an alternative to debugging, to finding ways to automatically check other project artifacts (like documentation and seed data), once you get hooked on having instant feedback for everything, you start to find all kinds of ways to apply it.
Probably the biggest effect, however, is how CT helps you write better tests. One of the points we made in the book goes like this:
An old axiom of Test Driven Development states that the tests test the correctness of the code; while the code, in turn, test the correctness of the tests. The tests also test the design of the code—code that’s hard to test is usually poorly designed. But what tests the design of the tests? In our experience, Continuous Testing is an effective way to test the design and overall quality of our tests...running our tests all the time creates a feedback loop that tells us when tests are misbehaving, as we create them. This means we can correct existing problems faster, and prevent bad tests from creeping into our system in the first place.
I'm very proud of what we've done with this book. I think it will be really valuable to anyone who's been writing automated tests and wants to get more out of them. I've been a doing TDD (and then BDD) since about 2003. My interest in continuous testing began in 2006 when I thought about all the time I was wasting figuring out which tests I needed to run after a change. After that, I wrote Infinitest, and now Continuous Testing with Ruby. I'm greatly looking forward to see where we go from here.