> yes but if you follow that too strongly you end up having to rework tests _every_ time you change something which is absurd. it depends how brittle your test

> yes but if you follow that too strongly you end up having to rework tests _every_ time you change something which is absurd. it depends how brittle your tests are. You can write tests that make sure internal stuff works at a unit level without them being so brittle to your point testing I/O or behavior is the way to accomplish this, but it can still be done at the level of internal functions/methods