A novel use of equivalent mutants for static anomaly detection in software artifacts

Abstract

Context: In mutation analysis, a mutant of a software artifact, either a program or a model, is said equivalent if it leaves the artifact meaning unchanged. Equivalent mutants are usually seen as an inconvenience and they reduce the applicability of mutation analysis.Objective: Instead, we here claim that equivalent mutants can be useful to define, detect, and remove static anomalies, i.e., deficiencies of given qualities: If an equivalent mutant has a better quality value than the original artifact, then an anomaly has been found and removed.Method: We present a process for detecting static anomalies based on mutation, equivalence checking, and quality measurement.Results: Our proposal and the originating technique are applicable to different kinds of software artifacts. We present anomalies and conduct several experiments in different contexts, at specification, design, and implementation level.Conclusion: We claim that in mutation analysis a new research direction should be followed, in which equivalent mutants and operators generating them are welcome.