Our results extending Kuhn's fault class hierarchy provide a justification for the focus of fault-based testing strategies on detecting particular faults and ignoring others. We develop a novel analytical technique which allows us to elegantly prove that the hierarchy applies to arbitrary expressions, not just those in disjunctive normal form. We also use the technique to extend the hierarchy to a wider range of fault classes. To demonstrate broad applicability, we compare faults in practical situations and analyze previous results. In particular, using our technique, we show that the basic meaningful impact strategy of Weyuker et. al. tests for stuck-at faults, not just variable negation faults.

Mutation analysis on model checking specifications is a recent development. This approach mutates a specification, then applies a model checker to compare the mutants with the original specification to automatically generate tests or evaluate coverage. The properties of specification mutation operators have not been explored in depth. We report our work on theoretical and empirical comparison of these operators. Our future plans include studying how the form of a specification influences the results, finding relations between different operators, and validating the method against independent metrics.

Available soon...