Beizer�s Phases in a Tester�s Mental Life: "Beizer�s Phases in a Tester�s Mental Life
Phase 0 = There�s no difference between testing and debugging. Other than in support of debugging, testing has no purpose.
Phase 1 = The purpose of testing is to show that the software works.
Phase 2 = The purpose of testing is to show that the software doesn�t works.
Phase 3 = The purpose of testing is not to prove anything, but to reduce the perceived risk of not working to an acceptable value.
Phase 4 = Testing is not an act. It is a mental discipline that result in low-risk software without much testing effort."