On a Combinatorial Framework for Fault Characterization

Covering arrays have been widely used to detect the presence of faults in large software and hardware systems. Indeed, finding failures that result from faulty interactions requires that all interactions that may cause faults be covered by a test case. However, finding the actual faults requires more, because the failures resulting from two potential sets of faults must not be the same. The combinatorial requirements on test suites to enable a tester to locate the faults are developed, and set in the context of similar combinatorial search questions. Test suites known as locating and detecting arrays to locate faults both in principle and in practice generalize covering arrays, thereby addressing combinatorial fault characterization. In common with covering arrays, these locating and detecting arrays scale logarithmically in size with the number of factors, but unlike covering arrays they support complete characterization of the interactions that underlie faults.