Time-travel testing of Android apps

Android testing tools generate sequences of input events to exercise the state space of the app-under-test. Existing search-based techniques systematically evolve a population of event sequences so as to achieve certain objectives such as maximal code coverage. The hope is that the mutation of fit event sequences leads to the generation of even fitter sequences. However, the evolution of event sequences may be ineffective. Our key insight is that pertinent app states which contributed to the original sequence's fitness may not be reached by a mutated event sequence. The original path through the state space is truncated at the point of mutation.