I wish I could write the unit test before the implementation, but I'm not that good, yet.
Or maybe I'm making excuses. Dunno.
Discussion
I just takes a new way of thinking/approaching the creation. I don't think it's necessarily more difficult, just a challenge to adjust from what you may be used to.
If you have a requirements spec, tests can usually be inspired from that to get the ball rolling.
I have an extremely detailed activity diagram and a list of user stories with acceptance criteria.
I use those for the manual test and the automated smoke test. Didn't even occur to me to use them for unit tests, as a sort of scaffold or implementation progress-bar, so thank you for the suggestion. I'm going to do that. 🤔
*follow*