The previous developer didn't write a freaking single test for a system that does a lot of calculations. Performance was shit so I got tasked with re-writing everything from DB queries to the actual calculation functions.

This has been the worst developer hell I've ever been. Without tests I cannot change anything without knowing if something breaks!!!

I gotta understand first the mess this guy left behind, then freaking write the tests that are missing and finally refactor the stuff. FML.

Btw, its Python and the guy didint even bother to do some basic type annotations so it's even worse. Function arguments are "data", "score", some are dicts, some are floats, some are lists.

Faaaaaaaaaaaaaack!!!!