You can use combinatorics to calculate the “total number of possible outcomes”. Here is an example: Four children, called A, B, C and D, sit randomly on four chairs. What is the probability that A sits on the first chair?

When do we use pairwise test?

Pairwise testing is used to test all the possible discrete combinations of the parameters involved. Pairwise testing is a P&C based method, in which to test a system or an application, for each pair of input parameters of a system, all possible discrete combinations of the parameters are tested.

What is combinatorial coverage?

Combinatorial coverage measures the proportion of t-way combinations of variable settings included in a test set, for specified levels of t. For example, with three binary variables a, b, and c, there are 12 possible 2-way settings: ab = 00, 01, 10, or 11, and likewise for ac and bc.