To be able to actually write useful tests BEFORE starting to code, which I guess is really asking for the ability to have a clear set of requirements and a complete mental model of the problem at hand

For which you usually need to make a lot of scribbles to have clear expectations beforehand. Haha, yeah, only if it was a magic.

Genie creates a gun, shows middle finger to you and shots himself.

Sounds a lot like TDD 😁
It doesn't require knowing everything up front. Explore as you go and tests help to navigate to the next step whilst making sure your next step forward didn't bring you 5 back without realising.
Would recommend a couple of talks from Ian Cooper if you have doubts. Especially the behaviour part. Will probably save hours on refactoring as you then don't need to update tests.