Software Testability: The New Verification

Software verification encompasses a wide range of techniques and activities that are geared towards demonstrating that software is reliable. Verification techniques such as testing provide a way to assess the likelihood that software will fail during use. This paper introduces a different type of verification that shows how likely it is that an incorrect program will not fail. Our verification applies fault-injection methods to predict where actual faults are more likely to hide. This verification can be combined with software testing to assess a confidence that the code is not hiding faults. Code that hides faults is difficult to test. In order to minimize the problem of hidden faults, we seek methods for identifying and isolating source code that is likely to hide faults. We also introduce the notion of "information loss," a characteristic that can be measured during the early phases of design to suggest where the planned software is likely to harbor faults that will be difficult to ..