Can you give an example of a testing method that checks all possible pairs of input data?

The testing method in which all possible pairs of input data are checked is called pairwise testing.

It is based on the assumption that most errors are caused by the interaction of two parameters. Instead of testing all possible combinations (which is often impossible due to their large number), pairwise testing covers all pairs of parameter values, significantly reducing the number of tests while maintaining high effectiveness.

Example: if there are three parameters with 3, 4, and 2 values respectively, full enumeration would result in 3×4×2=24 tests, while pairwise testing would involve fewer tests covering all pairs.