Is it a common use case to produce a standalone program that could be tested in isolation? Usually I'm asking for a function (or just a few lines of change) that depends on the rest of my code & environment, so it's not trivial to test.
if you're doing TDD style work but with an AI it's not uncommon to one-shot a function and then throw it against your battery of tests.
it's also pretty doable if you're writing smallish scripts or trying to follow functional coding paradigms; with functional stuff it's often easy to pick apart the specific modules for testing against criteria.