Semi-automatic Test Case Expansion for Mutation Testing

Mutation testing is the state-of-the-art technique for detecting weaknesses in a test suite. Unfortunately, alleviating these weakness (i.e. "killing the surviving mutants") is quite labour-intensive. In this paper we investigate a recommender system which expands test cases with extra asserts for the easy-to-fix mutants. We evaluated a proof-of-concept tool on ten open-source projects, and killed up to 6% of the surviving mutants. This illustrates that such a test expansion system would free up valuable time to address the harder-to-fix mutants.