From experience, it's amazingly easy to break something unintentionally when you're making changes, and even with a relatively small codebase it quickly becomes

From experience, it's amazingly easy to break something unintentionally when you're making changes, and even with a relatively small codebase it quickly becomes difficult to keep everything in your head. I'm not an advocate of TDD though, and I agree that more effort should be put into how to test.