Difference between regression, retesting and sanity

Question

Accepted Answer

Regression tests changes in existing functionality, retesting tests fixed defects, and sanity tests basic functionality.

Regression testing ensures that changes in code do not affect existing functionality.
Retesting is done to ensure that defects have been fixed and do not reoccur.
Sanity testing is a quick check to ensure that basic functionality is working as expected.
Regression and retesting are usually done after changes have been made to the code, while sanity testing is done before any major testing.
Example: After fixing a defect, retesting is done to ensure that the defect has been fixed and does not reoccur.
Example: After adding a new feature, regression testing is done to ensure that existing functionality has not been affected.
Example: Before starting any major testing, sanity testing is done to ensure that basic functionality is working as expected.

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