Using Mutants to Locate "Unknown" Faults

Many fault localization techniques operate by crosscutting coverage information of passed and failed test executions. Generally, their accuracy depends on the utilized coverage elements and on the selected test cases. This paper proposes a novel fault localization method using mutation and investigates its accuracy when using classical test selection criteria such as mutation, branch and block. A controlled experiment shows that (1) the mutation based approach is quite effective at identifying "unknown" faulty program statements. Additionally, the experimental results reveal (2) that the mutation-based test suites are significantly more effective at supporting fault localization than block or branch-based test suites. Further, (3) evidence in support of facilitating mutation alternatives, such as mutant sampling, in order to diminish mutation overheads is also given.