At 18: SAM: "So, when I found TDD it was like, "Wait, that's right. I've been an idiot. This is what computers are for. They can do these repetitive things over and over again and not complain." So, that's part of my motivation for writing tests first, is just that it reduces the cognitive load that I have to carry. As I'm working through a new problem I don't want to have to remember, "Oh, but then what happens in this case?" Like my interest there is to just write that down and have the computer tell me when I screw it up.
"Refactoring makes you smarter. Refactoring basically gives you an exobrain. So you offload a bunch of those little details that under normal circumstances go into working memory into your tests. Once you start refactoring you start reclaiming your brain."
"I want my feedback to be so fast that I can't think before it shows up. If I can think, then I'll sometimes lose attention, and I don't want to lose attention."
"The less you have to keep in mind, the smaller the chance that you'll make an error because you forgot one of the many details you needed to remember."
Pure functions also seem related. Less need to keep system state in your head: testing-concept-pure-functions-aid-testability