Allpairs

Allpairs refers to a set of approaches, tools, and concepts used in software testing to generate test suites that exercise all pairs of parameter values, i.e., two-way interactions, while keeping the total number of tests small. This methodology is commonly known as pairwise testing and is employed to detect defects resulting from interactions between two parameters more efficiently than exhaustive testing.

In practice, a test design task using allpairs starts with a list of input parameters, each with a finite domain of values. An allpairs algorithm constructs a collection of test cases such that for every pair of parameters, every combination of their values appears in at least one test case. This objective corresponds to creating a covering array CA(N, k, 2), where N is the number of test cases and k is the number of parameters. Algorithms for generating allpairs sets typically rely on greedy heuristics, combinatorial search, or constraint solving, and can be extended to higher-order t-wise testing to cover all t-way interactions if desired.

Tools and implementations of allpairs are widely available in software testing ecosystems. They accept input describing parameters and their possible values and produce a test suite that testers can execute. The main benefits are reduced testing effort and faster feedback compared to full factorial designs, while preserving important interaction coverage. Limitations include the possibility that the produced suite is not globally optimal, challenges when parameter values are highly constrained or interdependent, and diminished efficiency when the number of parameters or values grows large or when higher-order interactions are required.