Code Defenders: A Mutation Testing Game

Mutation testing is endorsed by software testing researchers for its unique capability of providing pragmatic estimates of a test suite's fault detection capability, and for guiding testers in improving their test suites. In practice, however, wide-spread adoption of mutation testing is hampered because any non-trivial program results in huge numbers of mutants, many of which are either trivial or equivalent, and thus useless. Trivial mutants reduce the motivation of developers in trusting and using the technique, while equivalent mutants are frustratingly difficult to handle. These problems are exacerbated by insufficient education on testing, which often means that mutation testing is not well understood in practice. These are examples of the types of problems that gamification aims to overcome by making such tedious activities competitive and entertaining. In this paper, we introduce the first steps towards building Code Defenders, a mutation testing game where players take the role of an attacker, who aims to create the most subtle non-equivalent mutants, or a defender, who aims to create strong tests to kill these mutants. The benefits of such an approach are manifold: The game can serve an educational role by engaging learners in mutation testing activities in a fun way. Experienced players will produce strong test suites, capable of detecting even the most subtle bugs that other players can conceive. Equivalent mutants are handled by making them a special part of the gameplay, where points are at stake in duels between attackers and defenders.