Something with enough context to write sensible test cases for a large codebase. It would be great if you could write test cases for a couple of domains, then ask it to write cases for a third domain following the same general style as the first. It would ideally have a conversation about what things to mock/stub and what things to keep.
I personally think 5 years isn’t enough time to get to that point with something that works really well. It’s tricky enough to get a junior up to speed with doing it sensibly, but cutting down on the time it takes to build a good test suite would mean we Devs can spend a lot more time on features and improvements.
Spain would probably be around that much if my calculations are correct.