I’ll edit my comment later since I’m on a phone it’s a bit late here but I have meddled with something similar for a mocking library but realized it could be useful in other scenarios, like what you mention.
I’ll put a link to the branch and repositories to give you a starting point if it’s something that you’re interested in, but it is basically a wrapper/spy that you can program.
There’s also a ruby library called suture by a company called testdouble that does something kind of similar to what you were mentioning, although their approach is more for mechanisms to refactor nasty code
