What Beauty Is External?
Consider a world-class distance athlete, such as an Olympic marathon runner or an Ironman triathlete. Such athletes have a rugged external beauty, a form-fits-function appearance. They are lean. They have extremely well-toned and well-defined—but usually not bulky—muscles. During their competitions, they show a determined face, and they bear the pain of the long event with grace. We can measure their effectiveness, efficiency, and elegance by their final times, their race standings, and their sportsmanlike behavior—win or lose.
A good test team also displays an external beauty, similar to a long-distance athlete. After all, testing is much more like a marathon than like a sprint!
Suppose that, by working with your testing stakeholders, you identify a number of objectives for testing. One includes a typical objective, that of finding bugs, especially important bugs. How might you determine your externally visible effectiveness and efficiency for this objective? Consider the following questions:
What percentage of the bugs delivered to us do we find?
Do we find a higher percentage of the important bugs?
What is our cost per bug found and fixed during testing compared to the cost of a failure in production?
For each of these questions, devise a metric. Start with the percentage of bugs that you find. You can measure this with the defect detection percentage (DDP), shown in Equation 2-1. If your testing is the last quality assurance activity prior to user acceptance ...