Combinations of equivalence classes Combinatorial explosion means that you cannot realistically test every possible system-wide equivalence class If there are 4 inputs with 5 possible values there are 54(i.e625)possible system-wide equivalence classes You should first make sure that at least one test is run with every equivalence class of every individual input You should also test all combinations where an input is likely to affect the interpretation of another You should test a few other random combinations of equivalence classes www.oseng.com C Lethbridge/Laganiere 2001 Chapter 10: Testing and Inspecting for High Quality 8© Lethbridge/Laganière 2001 Chapter 10: Testing and Inspecting for High Quality 8 Combinations of equivalence classes • Combinatorial explosion means that you cannot realistically test every possible system-wide equivalence class. —If there are 4 inputs with 5 possible values there are 5 4 (i.e.625) possible system-wide equivalence classes. • You should first make sure that at least one test is run with every equivalence class of every individual input. • You should also test all combinations where an input is likely to af ect the interpretation of another. • You should test a few other random combinations of equivalence classes