What is regression, smoke, and sanity testing?

These are different types of testing used to verify software quality:

• Regression testing: checking that new changes in the code haven't broken existing functionality. Usually performed after each change or release.

• Smoke testing: a superficial check of the main functions of the application to ensure the build is stable enough for further testing. Often called "build verification" or "build acceptance" testing.

• Sanity testing: a more focused check of a specific functionality or fix to ensure that the bug is truly fixed and no new errors have appeared.

Example:

• After the build, a smoke test is run to verify that the application launches and main pages open.
• If the smoke test passes, a sanity test is performed to verify the specific fix.
• Regression testing is run regularly to ensure that all functionalities work correctly.