Developing fault predictors for evolving software systems

Over the past several years, we have been developing methods of predicting the fault content of software systems based on measured characteristics of their structural evolution. In previous work, we have shown there is a significant linear relationship between code churn, a synthesized metric, and the rate at which faults are inserted into the system in terms of number of faults per unit change in code churn. We have begun a new investigation of this relationship with a flight software technology development effort at the jet propulsion laboratory (JPL) and have progressed in resolving the limitations of the earlier work in two distinct steps. First, we have developed a standard for the enumeration of faults. Second, we have developed a practical framework for automating the measurement of these faults. we analyze the measurements of structural evolution and fault counts obtained from the JPL flight software technology development effort. Our results indicate that the measures of structural attributes of the evolving software system are suitable for forming predictors of the number of faults inserted into software modules during their development. The new fault standard also ensures that the model so developed has greater predictive validity.