This document discusses all-pairs testing, also known as pairwise or combinatorial testing. It is a technique that generates a subset of combinations to test all possible pairs of input parameters in order to achieve high test coverage with fewer tests. The document provides an example of applying all-pairs testing to test the parameters of a car ordering application, including order category, location, car brand, registration number, order type, and order time. By using two representative values each for registration number and order time, the number of possible test case combinations is reduced from 240000 to 96, and further reduced to 8 cases by using all-pairs testing.