1. Quick Answer
Although both are quick verification techniques, Smoke Testing and Sanity Testing serve different purposes.
- Smoke Testing verifies the critical functionality of a new build to determine whether it is stable enough for further testing.
- Sanity Testing validates a specific bug fix or newly added functionality to ensure the change works correctly and has not affected nearby functionality.
In simple terms:
- Smoke Testing: "Is this build ready for testing?"
- Sanity Testing: "Did this specific change work correctly?"
2. Comparison at a Glance
| Aspect | Smoke Testing | Sanity Testing |
| Scope | Broad—critical functionality across the application | Narrow—only the affected module or fix |
| Depth | Shallow | More focused and deeper |
| Primary Goal | Verify build stability | Verify a specific fix or change |
| Documentation | Documented | Usually considered a subset of regression testing |
| Failure Result | Build is rejected | Build is rejected |
| Test Data | Positive test data | Focused around the modified functionality |
3. What Is Smoke Testing?
Smoke Testing verifies the application's critical functionality immediately after a new build is received.
Its purpose is to determine whether the build is stable enough for detailed testing.
Key Characteristics
- Verifies critical functionality.
- Confirms the build is testable.
- Uses positive test scenarios.
- Is documented.
- Acts as the first quality gate.
If the Smoke Test fails, further testing is typically stopped because the build is considered unstable.
4. What Is Sanity Testing?
Sanity Testing focuses only on the functionality that has recently changed.
It is commonly executed:
- After a defect has been fixed.
- After a new feature or module has been added.
- To ensure surrounding functionality has not been affected.
Sanity Testing is generally considered a subset of Regression Testing.
If the Sanity Test fails, the build is rejected until the identified issues are resolved.
5. Where BVT Fits
Build Verification Testing (BVT) determines whether a newly generated build is suitable for testing.
Purpose of BVT
- Verify the build before it reaches the QA team.
- Ensure critical application functionality works.
- Confirm the application is stable enough for further testing.
Characteristics
- Executed on every new build.
- Usually automated.
- Contains only critical test cases.
- Prevents unstable builds from reaching the testing team.
If BVT fails, the build is returned to the development team for correction.
From your testing notes, BVT is essentially a collection of critical regression test cases executed on every build and is commonly treated as a Smoke Test.
Best Practices for a BVT Suite
- Include only critical functionality.
- Keep the suite stable and reliable.
- Use predictable expected results.
- Ensure sufficient coverage of essential business workflows.
6. Testing Order: Smoke → Retesting → Sanity → Regression
The execution order is a common interview topic.
Step 1: Smoke Testing
Verify that the new build is stable enough for testing.
Step 2: Retesting
Validate that the reported defects have been fixed successfully.
Step 3: Sanity Testing
Verify the modified functionality and its surrounding components.
Step 4: Regression Testing
Ensure that recent changes have not introduced issues elsewhere in the application.
For complete explanations of each testing type, refer to the Complete Manual Testing Guide.
Frequently Asked Questions
What is the difference between Smoke Testing and Sanity Testing?
Smoke Testing verifies the critical functionality of an entire build to determine whether testing can continue.
Sanity Testing focuses only on recently modified functionality to ensure specific fixes or enhancements work correctly.
Which testing type comes first?
The typical execution order is:
- Smoke Testing
- Retesting
- Sanity Testing
- Regression Testing
Is Sanity Testing part of Regression Testing?
Yes.
Sanity Testing is generally considered a focused subset of Regression Testing because it verifies only the recently modified functionality.
What happens if Smoke Testing or Sanity Testing fails?
The build is rejected.
In the case of BVT or Smoke Testing, the build is usually returned to the development team before QA continues with additional testing.
What is Build Verification Testing (BVT)?
Build Verification Testing (BVT) is a set of automated tests executed on every new build to verify that the application is stable enough for detailed testing.
It primarily validates the application's critical functionality before the build is handed over to the testing team.