The Good-Enough Axiom: The scope of testing and acceptance are always compromises

Summary

Stakeholders and testers must jointly appreciate that there is no limit to testing and that the acceptance decision will always be made on incomplete evidence. In fact, acceptance may occur in spite of evidence, based on information known only to stakeholders.

Consequence if ignored or violated

Stakeholders are frustrated by poor system quality or late delivery because their expectations are unrealistic. Testers are frustrated because they cannot finish testing, the system is imperfect and stakeholders decide to accept regardless.

Questions

  • How much evidence from testing will be required to make the acceptance decision?
  • Who is authorised to make the acceptance decision?
  • What is the mechanism for assessing the value of evidence gathered during testing?
  • What coverage model(s) can be used to judge that enough evidence has been gathered?
  • What criteria will be used to judge that the system under test is acceptable or unacceptable?