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Testing and Quality: Correlation does not equal Causation

https://applitools.com/future-of-testing-apac/

How often have you heard:

“Our quality is poor, we need more testing (or testers).”

When you hear this, know that this indicates not only a spurious correlation but also a fundamental misunderstanding of what testing is or does.

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Testing and Quality: Correlation does not equal Causation

  1. 1. Testing and Quality: Correlation does not equal Causation Theresa Neate 25 June 2020 The Future of Testing - APAC 1
  2. 2. @TheresaNeate 25/6/20 About me QA Practice Lead @ REA Group DevOps Girls co-organiser & coach ~20 years of “IT experience” ~8 as Lead QA / Practice Lead 2 @TheresaNeate @DevOpsGirls theresaneate.com
  3. 3. @TheresaNeate 25/6/20 Today Testing 3 Quality Building in quality
  4. 4. @TheresaNeate 25/6/20 Famous last words “Our quality is poor, we need more testers (or testing).” 4
  5. 5. @TheresaNeate 25/6/20 Spurious Correlations 5 https://www.tylervigen.com/spurious-correlations
  6. 6. @TheresaNeate 25/6/20 Testing Testing is inspection & feedback 6 (not assurance) https://evanrudnickdiamonds.weebly.com/home/diamond-cuts-in-historic-europe
  7. 7. @TheresaNeate 25/6/20 Testing is disciplined 7 https://martinfowler.com/bliki/TestPyramid.html
  8. 8. @TheresaNeate 25/6/20 Minimise your manual testing But make it count 8 Beware “Inattentional Blindness” Appropriately involve testing personnel https://www.youtube.com/watch?v=vJG698U2Mvo
  9. 9. @TheresaNeate 25/6/20 Testing should be continuous 9 https://danashby.co.uk/2016/10/19/continuous-testing-in-devops/
  10. 10. @TheresaNeate 25/6/20 Quality “Quality is value to some person” – Jerry Weinberg 10
  11. 11. @TheresaNeate 25/6/20 Measuring quality (among others) Testing Static Analysis Linting Testability analysis BDD or TDD Continuous Integration UX research Monitoring and Alerting 11
  12. 12. @TheresaNeate 25/6/20 Improving Quality Reacting to the feedback, e.g. postmortems, bug triages, etc. 12 “You can’t ‘fix’ people, but you can fix systems and processes to better support people making the right choices when designing and maintaining complex systems.” – SRE Handbook
  13. 13. @TheresaNeate 25/6/20 Building In Quality Let’s take a proactive look 13
  14. 14. @TheresaNeate 25/6/20 Building In Quality - ideas Work slicing 14
  15. 15. @TheresaNeate 25/6/20 15 https://www.deltamatrix.com/horizontal-and-vertical-user-stories-slicing-the-cake/
  16. 16. @TheresaNeate 25/6/20 Building In Quality - ideas Reducing waste 16 https://theleanway.net/The-8-Wastes-of-Lean
  17. 17. @TheresaNeate 25/6/20 Building In Quality - ideas Flow 17 https://cloud.google.com/devops
  18. 18. @TheresaNeate 25/6/20 Building In Quality - ideas Just Culture 18 https://sidneydekker.com/just-culture/
  19. 19. @TheresaNeate 25/6/20 Building In Quality - ideas Collaboration & visibility: 19 Pair programming Pull requests *-driven-development Test coverage
  20. 20. @TheresaNeate 25/6/20 Building In Quality - ideas Systems thinking 20
  21. 21. @TheresaNeate 25/6/20 Moral of the story? Quality has both a proactive and reactive approach. Good testing is essential for valuable feedback. Think quality, not quantity. You cannot test in quality. 21
  22. 22. @TheresaNeate 25/6/20 Closing “Inspection is too late. The quality, good or bad, is already in the product.” – Deming 22
  23. 23. @TheresaNeate 25/6/20 References for this talk 23 Slides: theresaneate.com/content Blog: theresaneate.com/writing
  24. 24. @TheresaNeate 25/6/20 Thank you! 24

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