Why do Record/Replay Tests of Web Applications Break?

Software engineers often use record/replay tools to enable the automated testing of web applications. Tests created in this manner can then be used to regression test new versions of the web applications as they evolve. Web application tests recorded by record/replay tools, however, can be quite brittle, they can easily break as applications change. For this reason, researchers have begun to seek approaches for automatically repairing record/replay tests. To date, however, there have been no comprehensive attempts to characterize the causes of breakagesin record/replay tests for web applications. In this work, wepresent a taxonomy classifying the ways in which record/replay tests for web applications break, based on an analysis of 453 versions of popular web applications for which 1065 individual test breakages were recognized. The resulting taxonomy can help direct researchers in their attempts to repair such tests. It can also help practitioners by suggesting best practices when creating tests or modifying programs, and can help researchers with other tasks such as test robustness analysis and IDE design.