from experience, AI is bad at TDD. they can infer tests based on written code, but are bad at writing generalised test unless a clear requirement is given, so you the engineer is doing most of the work anyway.
Which, funny enough, is a pretty good reflection of how I thought of the people writing in those languages before LLMs: One considers testing a complete afterthought and in the wild it is rare to find tests at all, and when they are present they often aren't good. Whereas the other brings testing as a first-class feature and most codebases I've seen generally contain fairly decent tests.
No doubt LLM training has picked up on that.