Constructing Tests for DOM Events

In Chapter 1, we introduced the Interaction Rule, and noted that if all failures can be triggered by tway combinations or less, then testing all t-way combinations is in some sense equivalent to exhaustive testing. We have referred to this approach as pseudo-exhaustive testing [91]: clearly it is not exhaustive because we do not cover all possible inputs and issues such as timing and concurrency may be missed. But the ability to test all combinations of (discretized) values, up to the interaction strength actually involved in failures, provides a powerful assurance method. Can this approach really detect as many faults as completely exhaustive testing? Although it will take years of experience with combinatorial testing to give a full answer, this chapter summarizes two studies of practical problems where combinatorial and exhaustive approaches were compared. Results indicate that combinatorial testing can indeed find faults as well as exhaustive testing, using only a fraction of the tests.