SuMo: A mutation testing approach and tool for the Ethereum blockchain

capable of simulating a wide variety of traditional programming errors and Solidity-specific faults. The operators come in two flavors: Optimized, for faster mutation testing campaigns, and Non-Optimized, for performing a more thorough adequacy assessment. We implemented our approach in a proof-of-concept work, SuMo (SOlidity MUtator), and we evaluated its effectiveness on a set of real-world Solidity projects. The experiments highlighted a recurrent low Mutation Score for the test suites shipped with the selected applications. Moreover, analyzing the surviving mutants of a selected project helped us to identify faulty test cases and Smart Contract code. These results suggest that SuMo can concretely improve the fault-detection capabilities of a test suite, and help to deliver more reliable Solidity code.