Understanding Ineffective Events and Reducing Test Sequences for Android Applications

Monkey, which is integrated with the Android system, becomes the most widely used test input generation tool, owing to the simplicity, effectiveness and good compatibility. However, Monkey is based on coordinates of screen and oblivious to the widgets and the GUI states, which results in a great many ineffective events that have no contribution to the test. To address the major drawbacks, this paper parses the events of 200 test sequences generated by Monkey into human-readable scripts and manually investigate the effects of these events. We find three types of patterns on the ineffective events, including no-ops, single and combination of effect-free ones, and summarize them into ten rules for sequence reduction. Then, we implement a tool CHARD to match these patterns in real-world traces and prune the redundant events. The evaluation on 923 traces from various apps covering 16 categories shows that CHARD can process 1,000 events in a few seconds and identifies 41.3% events as ineffective ones. Meanwhile, the reduced sequence keeps the same functionality with the original one that can trigger the same behaviors. Our work can be applied to lessen the diagnose effort for record-and-replay, and as a preprocessing step for other works on analyzing sequences. For instance, CHARD can remove 72.6% ineffective events and saves 67.6% time of delta debugging in our experiments.