The ability of directed tests to predict software quality

Many statistical methods for estimating software quality rely on representative testing: they assume a program is tested in an environment that simulates the environment where it will be used. Often, however, a software tester’s aim is to uncover defects as soon as possible, and representative testing may not be the best way to do this. Instead, tests are often selected according to some plan that is believed to result in an efficient but thorough examination of the software’s behavior. This raises the question of how practical measurements of software quality, like software probabilitydofdfailure, can be obtained from directed testing. In this paper, we discuss some factors affecting the ability of directed tests to predict software quality when quality is measured in the environment where the software operates, but the directed tests do not simulate that environment. We consider a number of ways to measure the power of a directed test method, and show how these affect the tester’s ability to predict software quality.