A method to automate user interface testing using variable finite state machines

A method has been developed that allows automating a portion of interface testing. A core component of this method is a simple, yet flexible way to specify a formal model of a user interface, named variable finite state machines (VFSM). The model can be converted into an equivalent finite state machine, from which tests can be generated. The method has been applied to the user interface of Navigator II, a wearable computer system employed by aircraft repair personnel. A VFSM model of the interface was constructed and used to generate 5,968 tests, each composed of an input sequence and its corresponding expected output sequence. The tests were then applied to an instrumented form of the interface, and the results were compared to the expected output. From the data collected, three error sources were detected in the original interface that had escaped months of previous debugging efforts and field usage.