[disgruntledphd2]

Yeah, I'm a big fan of the Outside-In approach (I think it's from Michael Feathers's work).

The idea is that you test something at the very end of whatever you're working on, and ensure that it's identical to the original. You can then make larger changes to actually test the code properly while confirming that the overall system still works.

Super, super useful with ML things where running stuff can take a very looooonnnnnngggg time.