If you’ve been testing for any length of time, you know that the number of possible test cases is enormous if you try to test all possible combinations of inputs, configuration values, types of data, and so forth. It’s like the mythical monster, the many-headed Hydra, which would sprout two or more new heads for each head that was cut off. Two simple approaches to dealing with combinatorial explosions such as this are equivalence partitioning and boundary value analysis, but those techniques don’t check for interactions between factors. A reasonable, manageable way to test combinations is called pairwise testing, but to do it you’ll need a tool. In this inaugural One Key Idea session, Rex will demonstrate the use of a free tool, ACTS, built by the US NIST and available for download worldwide. We can’t promise to turn you into Hercules, but you will definitely walk away able to slay the combinatorial Hydra.