5.5Practical Guidelines

How Many Parameters Warrant Combinatorial Testing?

• 2-3 parameters: Test all combinations manually. Combinatorial tools are overkill.
• 4-7 parameters: Pairwise is the sweet spot. AI generation is fast and sufficient.
• 8-15 parameters: Use PICT or ACTS. AI-generated pairwise may miss pairs.
• 15+ parameters: You probably need to reduce the parameter space first. Consult with the team about which interactions actually matter.

How to Present This in Interviews

"For features with multiple interacting parameters, I use pairwise
combinatorial testing to reduce the test space. For a 5-parameter form
with 3-5 values each, this cuts 300+ combinations to about 16-20 tests
while covering all parameter pair interactions. I generate the initial
matrix using AI from the spec, verify coverage programmatically, then
convert it to parametrized tests. For larger parameter spaces or
safety-critical features, I use Microsoft PICT with AI-identified
constraints to get mathematically optimal coverage."