I’ve done the Evil Coder setup. I found it good as a game and a short group exercise, but also something that quickly lost its value/appeal after a short time.

The problem is, if you’re pairing on a real-world problem, if you play the Evil Coder, you need to remove yourself from solving the problem or communicating, which are both essential for pairing. Instead, you use this time to teach the other person what their tests actually do.

And if you’re not solving a real-world problem, it’s actually just practicing.

After that one time neither I, not my poring buddy at the time resorted to this practice any other time. We both got the point - not as much of an “aha” moment as I though it would be - and the red-green test approach works good enough for me.