Testing without mocking frameworks.
Over the years, my coding practices have changed a lot. From hacking away until it works to TDD/BDD/DDD and everything in between. One of the biggest changes in my developer career has been when, why, and how I test my code. In particular, my view on mocking frameworks has changed a lot. A couple of years ago I was convinced I could not live without them, now I wish I could do just that.