How effective are mutation testing tools? An empirical analysis of Java mutation testing tools with manual analysis and real faults

Mutation analysis is a well-studied, fault-based testing technique. It requires testers to design tests based on a set of artificial defects. The defects help in performing testing activities by measuring the ratio that is revealed by the candidate tests. Unfortunately, applying mutation to real-world programs requires automated tools due to the vast number of defects involved. In such a case, the effectiveness of the method strongly depends on the peculiarities of the employed tools. Thus, when using automated tools, their implementation inadequacies can lead to inaccurate results. To deal with this issue, we cross-evaluate four mutation testing tools for Java, namely PIT, muJava , Major and the research version of PIT, PIT RV , with respect to their fault-detection capabilities. We investigate the strengths of the tools based on: a) a set of real faults and b) manual analysis of the mutants they introduce. We find that there are large differences between the tools’ effectiveness and demonstrate that no tool is able to subsume the others. We also provide results indicating the application cost of the method. Overall, we find that PIT RV achieves the best results. In particular, PIT RV outperforms the other tools by finding 6% more faults than the other tools combined.