Pairwise Testing
// Definition
A combinatorial testing technique that constructs a minimal test suite in which every pair of distinct input parameters appears together in at least one test case — also called all-pairs testing. Research shows most software faults are triggered by interactions between at most two parameters, so pairwise coverage typically detects the same defects as exhaustive testing while reducing the test count from a multiplicative to roughly the square root of the full combination space.
// Related terms
Combinatorial Testing
A systematic approach to test design that selects a subset of all possible input combinations using mathematical techniques such as pairwise (all-pairs) or t-way coverage. Exhaustive combinatorial testing grows exponentially with the number of parameters, so combinatorial methods aim for maximum fault detection with the minimum test count. Pairwise coverage — ensuring every pair of parameter values appears in at least one test case — typically catches 70–90% of configuration-related defects at a fraction of the full combinatorial cost.
Equivalence Partitioning
Dividing the input space into groups where the system should behave identically, then testing one representative value per group. Reduces redundant test cases dramatically without losing coverage.
Test Coverage
A measure of which parts of the requirements or features have been exercised by tests. Distinct from code coverage — focuses on the spec, not the source.