LAUSR

Recording the sequence of events that lead to a failure of a web application can be an effective aid for debugging. Users can send a recording that results in a failure to a web application’s developer. The developer can then replay the recording, reproduce the failure, and find the fault(s) that cause it. Developers can do the same thing when faced with faults encountered in web applications in-house. A recording of an event sequence, however, may include many events that are not related to a failure, and this may render debugging more difficult. To address this problem, we have adapted Delta Debugging to function on recordings of web applications, in a manner that lets it identify and discard portions of those recordings that do not influence the occurrence of a failure, The resulting recording reduction technique can enable developers to localize faults based on reduced recordings instead of larger unreduced recordings, potentially reducing the amount of time and effort required to locate faults. We present the results of four empirical studies of our approach, in which we apply it to recordings created by Selenium IDE. In our first study we applied our technique to 30 faulty web applications obtained from developer forums, and showed that our technique could achieve significant reductions in recording size and replay time on these applications. In our second study we explored whether programmers could benefit from the use of reduced recordings when attempting to locate faults, and showed that our technique did increase their efficiency and effectiveness. In our third study we explored the scalability of our approach by applying it to substantially larger, more complex applications, and found that the approach worked even better on these larger applications than on the first set of smaller ones studied. In our fourth study we considered whether programmers working with two of these larger applications, who had more direct experience with the applications and the use of recordings and debugging could benefit from our technique. We found that the technique improved their efficiency and effectiveness, and the degree of improvement was even larger than that observed in our second study. Overall, these results suggest that recording reduction may be useful as means for helping programmers debug web applications.