SE401 · Annotated SlidesRegression Testing — Regression Testing
Regression Testing · Annotated slides

Regression Testing

Software evolution and why changes break things, what regression testing is, reasons for it, its problems (test-suite maintenance, obsolete and redundant tests, cost), and selecting and prioritizing regression tests (code-based, specification-based, prioritized rotating selection).

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      1. Changes (fixes, new features, refactoring, new environments) can break unchanged parts, uncover old bugs or reintroduce fixed ones.
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      1. Regression test: re-test a previously tested program after modification to make sure no new defects were introduced in unchanged areas.
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      Regression testing is performed:

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        1. Keep a test suite, run it after every change, compare with previous results, add new tests as needed.
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              1. Problems: maintaining the test suite, and the cost of re-testing (proportional to product size, not change size).
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                1. Obsolete test: no longer valid for the changed system. Redundant test: doesn’t differ significantly from others.
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                1. Selection: run only the tests relevant to the change. Prioritization: run the most important ones first when time is short.
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                1. Code-based selection: only tests that execute changed or new code.
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                Selecting only the tests that execute modified code is:

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                  1. Prioritized rotating selection: run all tests eventually, some sooner (round robin, track record of finding faults, structural coverage).
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