Test Data Design Techniques

Test design techniques reduce a large input space to a small, deliberate set of tests. Use the technique that matches the risk and behaviour.

Equivalence partitioning

Group values that should behave the same, then select a representative from each valid and invalid group.

Boundary value analysis

Defects often occur at edges. For the inclusive range 18–65, test:

Also consider empty, zero, maximum storage length, date changes, pagination edges and just-before or just-after time limits.

Decision tables

Use a table when combinations of rules produce different outcomes.

1. List conditions and actions.
2. Create meaningful combinations.
3. Remove impossible combinations.
4. Turn each remaining rule into a test.

Pairwise testing

Pairwise testing creates a small set where every pair of parameter values appears at least once. It is useful for combinations such as browser, operating system, language and user role.

State transitions

Use state-transition tests when allowed actions depend on the current state.

• Cover valid transitions.
• Attempt forbidden transitions.
• Check repeated events and interruptions.
• Verify history, notifications and permissions.

Practical approach

1. Write the rule in plain language.
2. Identify inputs, partitions, boundaries, combinations and states.
3. Select the smallest set that covers the important risk.
4. Add misuse, production defects and business-critical examples.
5. Record why each test exists.

Useful links

• ISTQB Foundation Level resources ↗
• Pairwise test generator ↗