An empirical study of incorporating cost into test suite reduction and prioritization

Software developers use testing to gain and maintain confidence in the correctness of a software system. Automated reduction and prioritization techniques attempt to decrease the time required to detect faults during test suite execution. This paper uses the Harrold Gupta Soffa, delayed greedy, traditional greedy, and 2-optimal greedy algorithms for both test suite reduction and prioritization. Even though reducing and reordering a test suite is primarily done to ensure that testing is cost-effective, these algorithms are normally configured to make greedy choices with coverage information alone. This paper extends these algorithms to greedily reduce and prioritize the tests by using both test cost (e.g., execution time) and the ratio of code coverage to test cost. An empirical study with eight real world case study applications shows that the ratio greedy choice metric aids a test suite reduction method in identifying a smaller and faster test suite. The results also suggest that incorporating test cost during prioritization allows for an average increase of 17% and a maximum improvement of 141% for a time sensitive evaluation metric called coverage effectiveness.