7 testing principles

7 testing principles

1. 1. testing shows the presence of defects

   • testing can show that defects are present, but cannot prove there are no defects
   • reduced probability of defects remaining, but not proof of correctness even if no defects are found

2. 2. exhaustive testing is not possible

   • testing everything is not possible except in very small cases
   • instead, we use risks and priorities to focus testing efforts

3. 3. early testing

   • testing activites should start as early as possible in SDLC
   • cheaper to find and fix defects
   • after development, objective should be to find as many integration, system defects as possible
   • find if the software meets user requirements
   • maintenance testing should be to ensure that there are no new defects - regression testing
   • asses system availability and reliability

4. 4. defect clustering

   • a small number of modules contain most of the defects discovered during pre-release or show the most failures
   • happens as an area of code is complex or tricky
   • testers use this info when making a risk assessment for planning the tests
     • focus on known hot spots

5. 5. pesticide paradox

   • if the same tests are repeated, the same set of test cases will no longer find any bugs
     • pesticide = !bugs

6. 6. testing is context dependent

   • testing is done differently in different contexts
   • safety critical software is tested differnelty to an e-commerce site
     • different level of risk

7. 7. absence-of-error fallacy

   • fixing and finding errors does not help if the system is unusable and DOES NOT meet users needs