What is the difference between smoke testing, sanity testing, and regression testing?
- smoke testing
- sanity testing
- regression testing
- test types
Answer it first, then compare. Nothing here is saved or scored.
Model answer
Smoke testing: broad, shallow check that the most critical features work after a build or deployment. "Does the application launch and can users log in?" Run first, fast, and frequently. Sanity testing: narrow, focused check that a specific fix or feature works correctly. "The login bug was fixed, does login work now?" Run after a targeted change. Regression testing: comprehensive check that existing functionality was not broken by recent changes. "Do all the features that worked before still work?" Run before releases. Order: smoke first (is it stable enough to test?), then sanity (does the specific fix work?), then regression (is everything else still fine?).
What interviewers listen for
- Risk-based prioritisationYou can defend skipping coverage on a path because the risk maths supports it.
- Test design fluencyYou apply equivalence partitioning and decision tables to concrete inputs in real time.
- Metric judgmentYou distinguish between metrics that drive learning and metrics that drive theatre.
- Strategy under constraintYou can produce a defensible plan when the team has half the time and twice the scope.