Object state testing and fault analysis for reliable software systems

Object state behavior implies that the eeect of an operation on an object may depend on the states of the object and other objects. It may cause state changes to more than one object. Thus, the combined or composite eeects of the object operations must be analyzed and tested. We show that certain object state behavior errors cannot be detected readily by conventional testing methods. We describe an object state test method consisting of an object state model, a reverse engineering tool, and a composite object state testing tool. The object state test model is an aggregation of hierarchical, concurrent, communicating state machines envisioned mainly for object state testing. The reverse engineering tool produces an object state model from any C++ program. The composite object state testing tool analyzes the object state behaviors and generates test cases for testing object state interactions. We show the detection of several composite object state behavior errors that exist in a well-known thermostat example.