ReSuMo: Regression Mutation Testing for Solidity Smart Contracts

Mutation testing is a powerful test adequacy assessment technique that can guarantee the deployment of more reliable Smart Contract code. Developers add new features, fix bugs, and refactor modern distributed applications at a quick pace, thus they must perform continuous re-testing to ensure that the project evolution does not break existing functionalities. However, regularly re-running the entire test suite can be time intensive, especially when mutation testing is involved. This paper presents ReSuMo, the first regression mutation testing approach and tool for Solidity Smart Contracts. ReSuMo uses a static, file-level technique to select a subset of Smart Contracts to mutate and a subset of test files to re-run during a regression mutation testing campaign. ReSuMo incrementally updates the mutation testing results considering the outcomes of the old program version; in this way, it can speed up mutation testing on evolving projects without compromising the mutation score.