What is Smoke Testing?
A smoke test is the fast sanity check that a build's vital functions work at all — can it start, log in, load the core screen, process one transaction — before deeper testing spends time on it. The name comes from hardware: power it on; if smoke appears, stop testing.
In CI pipelines, smoke tests are the first gate after deployment: minutes long, brutally shallow, and priceless — they convert "the release is broken somewhere" into "the release is broken, here, now, roll it back."
Worked example
Every deployment to staging triggers an eight-minute smoke suite: app boots, login works, search returns, one order completes end to end. Tuesday's build fails smoke in minute two — a config regression killed payments. Rollback happens before a single tester wastes an afternoon on a corpse, and before the demo scheduled at 3pm becomes an apology.