I Love Fast Tests
Since my post a couple days ago My First Sub-millisecond Test, I've been using this technique more and more. I can't emphasize enough how much more pleasant it is when test output looks like this:
Wow. TDD is not just a possibility when it you have this instant feedback, it almost feels like a necessity.
Again, it is SO easy to start using this. You don't have to go back and rewrite your tests, you don't have to spend weeks "building the project from scratch", you just start moving your new features (and consequently testing) outside of rails.
It's such an improvement that I decided to come in here and compose and publish this blog post while the "old" test suite is running for that application...