■ Input Testing
As noted in the introduction, the key advantage of combinatorial testing derives from the interaction rule: all, or nearly all, soware failures involve interactions of only a few parameters. Using combinatorial testing to select congurations can make testing more e cient, but it can be even more eective when used to select input parameter values. Traditionally testers develop scenarios of how an application will be used, then select inputs that will exercise each of the application features using representative values, normally supplemented with extreme values to test the performance and reliability. e problem with this oen ad hoc approach is that unusual combinations will usually be missed, so that a system may pass all tests and may work well under normal circumstances, but may eventually encounter a combination of inputs that it fails to process correctly. By testing all t-way combinations, for some specied level of t, combinatorial testing can help to avoid this type of situation.