Smoke test

A smoke test sends a harmless, clearly-marked test case through the same path a real one would take, and checks that each step succeeds. It is not exhaustive; it answers one fast question: is the whole chain alive right now?

Run before and after any change, it catches obvious breakage early, when it is cheap to fix, instead of after a real customer has already hit it. It cleans up after itself so the test data never pollutes real records.