Regression testing is a form of software testing that focuses on retesting past fixed bugs to verify that recent changes to the software have not reactivated the old bugs.
Regression testing is a form of software testing that focuses on retesting past fixed bugs to verify that recent changes to the software have not reactivated the old bugs. A software build in which old bugs resurface is said to have "regressed", in the sense that the software has taken a step backwards on the project completion timeline. Regression testing is typically done concurrently with unit testing, integration testing and systems testing and may be incorporated as a part of each of those testing phases.