Software Faults in Evolving a Large, Real-Time System: a Case Study

We report the results of a survey about the software faults encountered during the testing phases in evolving a large real-time system. The survey was done in two parts: the first part surveyed all the faults that were reported and characterized them in terms of general categories of faults; the second part surveyed in depth the faults found in the design and coding phases. For the first part, we describe the general faults found and characterize the requirements, design and coding faults by the testing phases in which they were found and how they were found over time during the testing phases. For the second part, we describe the questionaire used to survey the design and coding faults, report the faults that occurred, how difficult they were to find and to fix, what their underlying causes were (that is, what their corresponding errors were), and what means might have prevented them from occurring; we then characterize the results in terms of interface and implementation faults.