5.1The Combinatorial Explosion Problem

When you have multiple input parameters, exhaustive testing is impractical. A user registration form with 5 parameters, each with 3-5 values, produces hundreds or thousands of combinations. Testing all of them is expensive and most combinations do not reveal unique bugs.

Combinatorial test design solves this by selecting a subset of combinations that guarantees every pair (or n-tuple) of parameter values appears in at least one test case. This dramatically reduces test count while maintaining high defect detection.