Test-Based Clone Detection: an Initial Try on Semantically Equivalent Methods

Most code clone detection approaches identify clones via static source code analysis. Such approaches are effective and efficient in detecting lexically similar clones. However, they are less effective in detecting semantic clones that are similar in functionality but different in implementation. As an initial try to detect semantic clones, in this paper, we propose a test-based approach to detecting methods that are semantically equivalent to API methods. For a given method m, we generate its test cases automatically and search for semantically equivalent API methods by running the generated test cases. If two methods generate the same output on each of the test cases, they are taken as semantically equivalent methods. One of the weakness of test-based clone detection is that it is often time consuming. To reduce the time complexity, we take the following measures. First, we focus on methods instead of arbitrary fragments. Second, for a given method, we only compare it against such API methods whose signatures are highly similar to that of the given method. We evaluate the proposed approach on 10 well-known applications. Evaluation results suggest that it is efficient and accurate, and its precision is up to 98%.