This is why you write the tests first before the actual code.

I've seen some interesting thoughts on TDD with fail, pass, refactor assumptions. I'm curious if anyone here is writing functional code in order to then make a failing functional test pass i.e. BDD / ATDD. This follows similar logic without the refactor assumption. I've seen strong opinions on every side as far as this is concerned. On a team with Dev and QA competencies, I've heard a number of devs glad to get QA out of the bottleneck and put their knowledge to better use.

Meaning your tests where to complex.

If you use your type system to make invalid states impossible to represent & your functions are pure, there less—maybe nothing—to test, which will save you from this scenario.