Unit Tests for LLMs?

is theres any package that helps do like vitest style like quick sanity checks on the output of an llm that I can automate to see if I have regressed on smthin while changing my prompt.

For example this agent for a realtor kept offering virtual viewings (even though that isnt a thing) instead of doing a handoff, (modified prompt for this) so a package where I can write a test so that, hey for this input, do not mention this or never mention those things. Or for certain inputs, always call this tool.

Started engineering my own little utility for this, but before I dove deep and built my own package, wanted to see if something like this alr exists or if im heading down the wrong path here!

p.s. not sure if this should be called evals, kinda overlapping but yeah what should this even be called?