Smoke Tests

Smoke tests

A smoke suite answers one question fast: is this build alive enough to serve users? It is not comprehensive and should not try to be. Its job is to catch the deploy that broke login, took down the homepage, or lost the database connection, within a few minutes of shipping, so promotion halts before the damage reaches everyone. When smoke tests grow into a full regression suite, they stop gating deploys because nobody waits for them.

Method

1. Pick the handful of paths that mean "the app works." Can a user log in, can they complete the one core action, does the homepage return 200, is the database reachable. Five to ten checks, chosen because their failure is an outage, not because they are easy to write.
2. Time-box the whole suite to five minutes. It runs on every deploy, so it must finish before anyone reasonably waits. If it creeps past the budget, cut the least critical check rather than adding parallelism forever.
3. Run it against the deployed environment, not a mock. Point the suite at the real, just-deployed instance: hit its health endpoint and drive a few genuine transactions through it. The point is to prove this build in this environment came up correctly.
4. Fail loud and block promotion on the first red. A smoke failure stops the rollout or triggers rollback immediately, with no "known flaky, proceed anyway." The gate only means something if a failure actually holds the line.
5. Assert on user-visible outcomes and keep every step stable. Check that the confirmation appears and the status is 200, not that an internal counter moved. Zero tolerance for a flaky step here: a smoke test that cries wolf gets ignored, which defeats the gate.
6. Layer smoke checks per stage. A build smoke (does it start, do health checks pass) and a post-deploy smoke (do core journeys work in the live environment) catch different failures at the cheapest possible point.

Litmus tests

• Does the full suite finish inside the five-minute budget?
• Would every check's failure genuinely warrant blocking or rolling back the deploy?
• Is the suite free of any step known to flake?

Boundaries

Smoke tests are a thin, fast gate, deliberately shallow. Deep coverage of features belongs to integration-testing and unit tests, whole journeys to e2e-testing, and verification under live traffic to testing-in-production. Deciding which paths count as critical is a product call: confirm the list with whoever owns the deploy.