Abstract
This paper presents an empirical study on the effects of the quantity of faults on statistical, coverage-based fault localization techniques. The former belief was that the effectiveness of fault-localization techniques was inversely proportional to the quantity of faults. In an attempt to verify these beliefs, we conducted a study on three programs varying in size on more than 13,000 multiple-fault versions. We found that the influence of multiple faults (1) was not as great as expected, (2) created a negligible effect on the effectiveness of the fault localization, and (3) was often even complimentary to the fault-localization effectiveness. In general, even in the presence of many faults, at least one fault was found by the fault-localization technique with high effectiveness. We also found that some faults were localizable regardless of the presence of other faults, whereas other faults’ ability to be found by these techniques varied greatly in the presence of other faults. Because almost all real-world software contains multiple faults, these results impact the use of statistical fault-localization techniques and provide a greater understanding of their potential in practice.
