A Predicate-Based Software Testing Strategy*

In this paper, we describe the basic theory underlying BOR (boolean operator) testing and BRO (boolean and relational operator) test-selection criteria, and discuss experimental evidence that shows that BOR testing requires a far smaller number of test-cases than some more traditional strategies, while retaining fault-detection capabilities that are as good as, or better than these strategies. The approach we describe can be used to develop test cases based on software specifications, or based on the implementation, that is, it can be used for both functional and structural testing. We evaluate the BOR strategy with respect to branch testing, traditional causeeffect graph testing, and informal functional and random testing. Two simulation experiments showed that BOR testing is very effective at detecting faults in predicates. We also performed two experiments where we applied BOR strategy to software specification cause-effect graphs of a real-time control system and a set of N-version programs. Our results indicate that BOR testing is practical, and has detected faults that the previously applied strategies have not.