Regression testing

Regression testing (rarely, non-regression testing) is re-running functional and non-functional tests to ensure that previously developed and tested software still performs as expected after a change. If not, that would be called a regression.

Changes that may require regression testing include bug fixes, software enhancements, configuration changes, and even substitution of electronic components (hardware). As regression test suites tend to grow with each found defect, test automation is frequently involved. The evident exception is the GUIs regression testing, which normally must be executed manually. Sometimes a change impact analysis is performed to determine an appropriate subset of tests (non-regression analysis).