Regression testing is a type of software testing that ensures that previously developed and tested software still performs the same way after it is changed or interfaced with other software. Changes may include software enhancements, patches, configuration changes, etc. During regression testing, new software bugs or regressions may be uncovered. Sometimes a software change-impact analysis is performed to determine which areas could be affected by the proposed changes. These areas may include functional and non-functional areas of the system.
The purpose of regression testing is to ensure that changes such as those mentioned above have not introduced new faults.[1] One of the main reasons for regression testing is to determine whether a change in one part of the software affects other parts of the software.[2]
Common methods of regression testing include re-running previously completed tests and checking whether program behavior has changed and whether previously fixed faults have re-emerged. Regression testing can be performed to test a system efficiently by systematically selecting the appropriate minimum set of tests needed to adequately cover a particular change.