> Generally though the best way to get good tests out of a coding agent is to make sure it's working in a project with an existing test suite that uses good patterns. Coding agents pick the existing patterns up without needing any extra prompting at all.

Yeah, this is where I too have seen better results. The worse ones have been in places where it was greenfield and I didn't have an amazing idea of how to write tests (a data person working on a django app).

Thanks for the information, that's super helpful!