Difference between regression, sanity and smoke tests?

 Regression Testing:

• Testing conducted on modified build to make sure that, there will be no impact on existing functionality by changing (adding /deleting /modifying) the application features.
• It is a black box testing technique.

When we can perform Regression testing:

• When new functionality added to the application.
• when there is change in requirement.
• After fixing the defect.
• When there is a performance change.

Regression Testing process:

Sanity Test:

• Sanity is done during the release phase to check for the main application without going deeper.
• The test is done in a stable build.
• It is a part of the regression testing.
• It is planned when there is no time to do in-depth testing.

Smoke Testing:

• Smoke testing is done to make sure the build we receive from the development team is stable or not.
• It is performed by both developers and testers.
• Here the build may be either stable or unstable.
• It is done on initial building.
• Smoke test is done every time when the new build is released.