Decision Table Testing

Learning objectives#

• Build a decision table
• Derive test cases from rules
• Collapse impossible or irrelevant rules
• Spot missing requirements

Explanation#

List the conditions (inputs) and actions (outcomes). With n yes/no conditions there are 2ⁿ rules.

Each column is a rule: a combination of condition values and the expected actions.

Remove impossible combinations and merge rules where a condition does not matter (“–”).

Building the table often exposes gaps in requirements — ask about them.

Code example: Instant loan approval#

1Conditions                  R1   R2   R3   R4
2Salary ≥ ₹25,000?           Y    Y    N    N
3Credit score ≥ 700?         Y    N    Y    N
4Actions
5Approve instantly           X
6Send to manual review            X    X
7Reject                                     X
8

9Tests: one per rule → 4 test cases
10Question raised: what happens if the applicant is under 21? (not in requirement)

Four tests cover every combination, and the table revealed a missing age rule.

This example is illustrative. Copy or download it and run it in your own environment; the expected output is shown above.

Step-by-step explanation#

1. List conditions and actions from the requirement.
2. Fill all combinations as rules.
3. Mark the expected actions for each.
4. Write one test per rule and query gaps.

Real-world use case#

Common mistakes#

Best practices#

• Use tables for business rules
• Review the table with the BA
• Collapse irrelevant conditions
• Keep one test per rule

Remember this#

Practice exercise#

12³ = 8 rules.

Mini quiz#

Want more? Practise all Manual Testing MCQs · Manual Testing interview questions

Related topics#

My notes#

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