How would you test a form with many combinations of options?

The problem: a flight search form with 4 trip types, 3 cabin classes, 5 passenger counts, 2 currencies and 3 languages has 4 x 3 x 5 x 2 x 3 = 360 combinations. Testing all of them is not realistic.

Pairwise (all-pairs) testing: most bugs are caused by a single value or by the interaction of two values. Pairwise testing creates a small set of tests where every pair of values appears at least once. For the form above, that is about 20 tests instead of 360.

How I do it

1. List the fields and the values for each, using equivalence partitions (not every number from 1 to 9, but 1, a typical value and the maximum).
2. Generate the combinations with a tool like PICT or an online pairwise generator.
3. Add constraints for impossible combinations (an infant can’t travel alone).
4. Add risk-based extras: combinations that matter to the business or have failed before, like “one-way, business class, 9 passengers, EUR”.
5. Test each field on its own for validation and boundaries too.

Pairwise is a smart way to reduce tests, not a guarantee. A bug that needs three specific values together can still slip through, so I combine it with the risky combinations I know about.

Learn more: Equivalence Partitioning