1. (c) Dr. Wolfgang J. Schneider 2003 - 2006 GENERAL TESTING PRINCIPLES Dr. Wolfgang J. Schneider 2003 – 2006

2. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Acknowledgement Most of the content has been developed by ISTQB and its affiliates for fair use. The copy right of those parts is with them. The layout has been developed by us.

3. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles INTRODUCTION Over the past 40+ years, a number of testing principles have been suggested by different authors. They offer general guidelines common for all testing.

4. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

5. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

6. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

7. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

8. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

9. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

10. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

11. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

12. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

13. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects

14. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects Testing can show you that defects are there. Testing cannot prove that there are no defects.

15. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects Testing can show you that defects are there. Testing cannot prove that there are no defects.

16. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects Testing can show you that defects are there. Testing cannot prove that there are no defects.

17. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects

18. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects Testing reduces the probability of undiscovered defects remaining in the software. But, even if no defects are found, it is not a proof of correctness.

19. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects Testing reduces the probability of undiscovered defects remaining in the software. But, even if no defects are found, it is not a proof of correctness.

20. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects Testing reduces the probability of undiscovered defects remaining in the software. But, even if no defects are found, it is not a proof of correctness.

21. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing shows Presence of Defects Testing cannot prove that there are no defects. If no defects are found, it is not a proof of correctness.

22. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Exhaustive Testing is Impossible

23. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Exhaustive Testing is Impossible Testing everything (all combinations of inputs and preconditions) is not feasible except for trivial cases. Instead of exhaustive testing, we use risk and priorities to focus testing efforts.

24. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Exhaustive Testing is Impossible Testing everything (all combinations of inputs and preconditions) is not feasible except for trivial cases. Instead of exhaustive testing, we use risk and priorities to focus testing efforts.

25. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Exhaustive Testing is Impossible Testing everything (all combinations of inputs and preconditions) is not feasible except for trivial cases. Instead of exhaustive testing, we use risk and priorities to focus testing efforts.

26. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Exhaustive Testing is Impossible Testing everything (all combinations of inputs and preconditions) is not feasible except for trivial cases. Instead of exhaustive testing, we use risk and priorities to focus testing efforts.

27. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Early Testing

28. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Early Testing Testing activities should start as early as possible in the software or system development life cycle They should be focused on defined objectives

29. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Early Testing Testing activities should start as early as possible in the software or system development life cycle They should be focused on defined objectives

30. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Early Testing Testing activities should start as early as possible in the software or system development life cycle They should be focused on defined objectives

31. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Early Testing Testing activities should start as early as possible in the software or system development life cycle They should be focused on defined objectives

32. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Early Testing Testing activities should start as early as possible in the software or system development life cycle They should be focused on defined objectives

33. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Defect Clustering

34. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Defect Clustering A small number of modules contain most of the defects discovered during pre-release testing, or show the most operational failures.

35. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Defect Clustering A small number of modules contain most of the defects discovered during pre-release testing, or show the most operational failures. A SMALL NUMBER OF MODULES CONTAIN MOST OF THE DEFECTS

36. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Pesticide Paradox

37. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Pesticide Paradox If the same tests are repeated over and over again, eventually the same set of test cases will no longer find any new bugs.

38. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Pesticide Paradox Most vintage testers call this the Mine Field Effect Mine Field Effect http://www.testingeducation.org/k04/documents/bbstRegression2005.ppt

39. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Pesticide Paradox To overcome this effect, the test cases need to be regularly reviewed and revised, and new and different tests need to be written to exercise different parts of the software or system to potentially find more defects.

40. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing is Context Dependent Testing is done differently in different contexts. For example, safety-critical software is tested differently from an e-commerce site.

41. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing is Context Dependent Testing is done differently in different contexts. For example, safety-critical software is tested differently from an e-commerce site.

42. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing is Context Dependent Testing is done differently in different contexts. For example, safety-critical software is tested differently from an e-commerce site.

43. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing is Context Dependent Testing is done differently in different contexts. For example, safety-critical software is tested differently from an e-commerce site.

44. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Testing is Context Dependent Testing is done differently in different contexts. For example, safety-critical software is tested differently from an e-commerce site. RISK

45. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Absence-of-Errors Fallacy Finding and fixing defects does not help if the system built is unusable and does not fulfill the users needs and expectations and expectations

46. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Absence-of-Errors Fallacy Finding and fixing defects does not help if the system built is unusable and does not fulfill the users needs and expectations

47. (c) Dr. Wolfgang J. Schneider 2003 - 2006 Absence-of-Errors Fallacy Finding and fixing defects does not help if the system built is unusable and does not fulfill the users needs and expectations

48. (c) Dr. Wolfgang J. Schneider 2003 - 2006 GENERAL TESTING PRINCIPLES

49. (c) Dr. Wolfgang J. Schneider 2003 - 2006 General Testing Principles Testing shows Presence of Defects Testing shows Presence of Defects Exhaustive Testing is Impossible Exhaustive Testing is Impossible Early Testing Early Testing Defect Clustering Defect Clustering Pesticide Paradox Pesticide Paradox Testing is Context Dependent Testing is Context Dependent Absence-of-Errors Fallacy Absence-of-Errors Fallacy

50. DR. WOLFGANG J. SCHNEIDER GMBH International Information Technology Consultants Professional Testing Solutions Telecommunications and Utility Billing Systems Euro Preparation for Companies in New EU Member Countries EDIFACT – DATANORM – ELDANORM – ETIM Interfaces Data Exchange with Banks and Credit Card Companies Total Quality Management – Good Manufacturing Practices IT Service Management - IT Infrastructure Library (ITIL) Knowledge Management Solutions IT Fitness for GAAP – IAS – FASB Balanced Scorecard Take Advantage of 30+ Years of IT Experience ! www.drschneider.eu Dr. Wolfgang J. Schneider - Start