ABSTRACT
The use of equivalence classes as the basis for functional testing has two motivations: we would like to have a sense of complete testing, and, at the same time, we would hope to avoid redundancy. Neither of these hopes is realized by boundary value testing—looking at the tables of test cases, it is easy to see massive redundancy, and looking more closely, serious gaps exist. Equivalence class testing echoes the two deciding factors of boundary value testing, robustness and the single/multiple fault assumption. This chapter presents the traditional view of equivalence class testing, followed by a coherent treatment of four distinct forms based on the two assumptions. The single versus multiple fault assumption yields the weak/strong distinction and the focus on invalid data yields a second distinction: normal versus robust. Taken together, these two assumptions result in Weak Normal, Strong Normal, Weak Robust, and Strong Robust Equivalence Class testing.
