I always suspect that many people who have a hard time relating to TDD already have experience writing these class & method oriented tests. So they understandably struggle with trying to figure out how to write them before writing the code.

Thinking about tests in terms of product features is how it clicked for me.

That being said, as another poster above mentioned, using TDD for unstable or exploratory features is often unproductive. But that’s because tests for uncertain features are often unproductive, regardless if you wrote them before or after.

I once spent months trying to invent a new product using TDD. I was constantly deleting tests because I was constantly changing features. Even worse, I found myself resisting changing features that needed changing because I was attached to the work I had done to test them. I eventually gave up.

I still use TDD all the time, but not when I’m exploring new ideas.