What is the main difference between smoke testing and sanity testing?

Smoke testing checks whether the core functionality of an entire build works at a basic level — it's broad and shallow. Sanity testing checks whether a specific bug fix or feature works correctly after changes — it's narrow and deep. Smoke tests answer 'is this build stable enough to test further?' while sanity tests answer 'does this specific change work as expected?'

Which comes first, smoke testing or sanity testing?

Smoke testing comes first. It is performed on a new build to verify basic stability before any further testing begins. Sanity testing comes later, after bug fixes or minor changes, to verify that the specific changes work without a full regression cycle.

Can smoke testing and sanity testing be automated?

Yes. Smoke tests are excellent candidates for automation because they run on every new build and cover the same core flows. Sanity tests can also be automated, especially when they target specific regression areas. Tools like Bugster can automate both by running targeted test suites on every pull request.

Is smoke testing the same as regression testing?

No. Smoke testing is a quick, surface-level check of core functionality to decide if a build is testable. Regression testing is a thorough re-testing of the entire application (or large parts of it) to ensure that changes haven't broken existing features. Smoke tests take minutes; regression tests can take hours or days.

Who performs smoke testing vs sanity testing?

Smoke testing is often performed by the QA team or automated CI pipelines immediately after a new build is deployed. Sanity testing is usually performed by testers who are familiar with the specific area that was changed, or by the developer who made the fix.

Smoke Testing vs Sanity Testing — Differences

What Is Smoke Testing?

Smoke testing is a preliminary check performed on a new software build to verify that the most critical functions work. The name comes from hardware testing — if you plug in a circuit board and it literally smokes, there is no point testing anything else. In software, a smoke test answers one question: is this build stable enough to proceed with deeper testing?

Smoke tests are broad but shallow. They cover the main user paths — login, navigation, core business logic — without going into detail. If a smoke test fails, the build is rejected and sent back to development. If it passes, the QA team moves on to more thorough testing.

Typical smoke test examples include: can the application launch, can a user log in, does the main dashboard load, and can the primary workflow complete without crashing.

What Is Sanity Testing?

Sanity testing is a focused check performed after receiving a build with minor changes — usually bug fixes or small feature additions. It verifies that the specific changes work as intended and that closely related functionality has not been broken. Sanity testing answers: does this particular fix or change make sense and work correctly?

Unlike smoke testing, sanity tests are narrow but deeper. They concentrate on the area that was changed rather than the whole application. For example, if a developer fixed a checkout calculation bug, the sanity test would verify the fix works with various inputs, check edge cases around the calculation, and confirm that related features like tax and shipping still work.

Sanity testing is usually unscripted and relies on the tester's knowledge of the feature area. It is faster than a full regression test but more targeted than a smoke test.

Side-by-Side Comparison

Aspect	Smoke Testing	Sanity Testing
Purpose	Verify build stability	Verify specific changes
Scope	Broad and shallow	Narrow and deep
When	After every new build	After bug fixes or minor changes
Scripted?	Usually yes (documented test cases)	Usually no (exploratory)
Performed by	QA team or CI pipeline	Testers familiar with the area
If it fails	Build is rejected entirely	Specific fix is sent back
Automation	Highly automatable	Can be automated for known areas

When to Use Each

Use smoke testing when a new build is deployed to the test environment. It is the first gate — if the smoke test fails, there is no point running other tests because the build is fundamentally broken. Smoke tests should be automated and run in your CI/CD pipeline on every deployment.

Use sanity testing when you receive a build with targeted fixes or changes and need to quickly verify they work without running the full regression suite. It saves time by focusing only on the changed areas and their immediate dependencies.

In practice, most teams use both: smoke tests on every build, followed by sanity tests for specific changes, and periodic full regression testing for comprehensive coverage.

Automating Smoke and Sanity Tests

Both testing types benefit enormously from automation. Automated smoke tests can run in minutes on every build, giving instant feedback on build stability. Automated sanity tests can target specific feature areas based on which files changed in a pull request.

Tools like Bugster run end-to-end tests on every pull request, effectively combining smoke and sanity testing into a single automated step. AI agents test your critical user flows (smoke) and also focus on areas affected by the code change (sanity), catching issues before they reach production.