You can prompt an LLM to generate tests from the spec and I'd bet it would easily get most of the way there, especially if you give it a reference implementation to test against. I did just that, though on a small scale - just for feature tests. The last few percent would be the real challenge, you probably don't want it to just imitate another implementation's bugs.

Reference implementation that someone else — a human, wrote? Hm… so one way or another, some humans’ labour is laundered…