The Economics of Software Quality

Chapter 4. Pretest Defect Removal

Introduction

Testing is the traditional form of software defect removal. Indeed, testing is the only form of defect removal for many software applications. But after more than 50 years of software history, data on testing costs and testing effectiveness demonstrate that both testing efficiency and testing expenses are directly related to pretest activities.

If test cases are designed using requirements and specification documents that contain serious errors, then test cases tend to confirm these upstream errors rather than weed them out. This explains why testing did not find the Y2K defect for many years. Because two-digit dates were not thought of as defects, no methods found them. Far-sighted quality analysts ...