Functional Broadside Tests with Different Levels of Reachability

Functional broadside tests for transition faults are broadside tests that detect transition faults using only states that the circuit can visit during functional operation, or reachable states. Reachability was used before as a binary property, i.e., a state is either reachable or not. This concept was extended to associate a level of reachability with every state. A non-zero level is associated with a reachable state. A reachable state that is more likely to occur during functional operation is associated with a higher reachability level than a state that is less likely to occur. Tests based on states with high levels of reachability and tests based on states with low levels of reachability can serve different purposes, and both may be needed for a high-quality test set. A process of constructing a test set for transition faults was described such that each detectable fault would be detected by two functional broadside tests with the most extreme possible levels of reachability