Mining API Usage Examples from Test Code

Abstract—Lack of effective usage examples in API documents has been proven to be a great obstacle to API learning. To deal with this issue, several approaches have been proposed to automatically extract usage examples from client code or related web pages, which are unfortunately not available for newly released API libraries. In this paper, we propose a novel approach to mining API usage examples from test code. Although test code can be a good source of usage examples, the issue of multiple test scenarios might lead to repetitive and interdependent API usages in a test method, which make it complicated and difficult to extract API usage examples. To address this issue, we study the JUnit test code and summarize a set of test code patterns. We employ a code pattern based heuristic slicing approach to separate test scenarios into code examples. Then we cluster the similar usage examples for recommendation. An evaluation on four open source software libraries demonstrates that the accuracy of our approach is much higher than the state-of-art approach eXoaDoc on test code. Furthermore, we have developed an Eclipse plugin tool UsETeC. Keywords—API; usage example; test code; code patterns; code slicing I