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Decision Table Testing

Decision Table Testing is a test case design technique used to validate complex business rules by representing different input conditions and their corresponding actions in a structured tabular format.

Decision table testing answers: “What should the system do for each possible combination of conditions?”

1. Definition

Decision Table Testing is a test case design technique used to validate complex business rules by representing different input conditions and their corresponding actions in a structured tabular format.

Decision table testing answers: “What should the system do for each possible combination of conditions?”

2. Purpose of Decision Table Testing

  • Handle complex conditional logic
  • Ensure complete coverage of business rules
  • Identify missing or conflicting rules
  • Reduce ambiguity in requirements

3. When to Use Decision Table Testing

  • Multiple conditions affect the outcome
  • Business rules involve combinations of inputs
  • Rule-based systems (banking, insurance, pricing)

4. Structure of a Decision Table

A decision table has four parts:

  1. Conditions
  2. Condition values (Yes/No, True/False)
  3. Actions
  4. Action outcomes

5. Simple Decision Table Example

Rule: Loan approval depends on Age and Income.

Conditions Rule 1 Rule 2 Rule 3 Rule 4
Age ≥ 21 Yes Yes No No
Income ≥ Min Yes No Yes No
Action: Approve Loan Yes No No No

Each column represents one test case.

6. Steps to Create Decision Table Test Cases

  1. Identify all conditions
  2. List all possible condition combinations
  3. Define expected actions
  4. Create test cases for each valid rule

7. Decision Table Testing vs Other Techniques

Technique Best For
Decision Table Multiple condition combinations
BVA Boundary values
EP Input grouping

8. Real-Time Example

Discount rules:

  • Customer type (Regular / Premium)
  • Purchase amount (> $500 / ≤ $500)

Decision table ensures all combinations are tested.

9. Common Mistakes

  • Missing condition combinations
  • Too many combinations without prioritization
  • Incorrect expected actions

10. Interview-Ready Answers

Short answer:

Decision table testing is used to test multiple condition combinations and their corresponding outcomes.

Detailed answer:

Decision table testing represents business rules in a tabular format to ensure all condition combinations are validated systematically.

11. Key Takeaway

Decision Table Testing is ideal for rule-heavy and logic-driven systems, ensuring no condition combination is missed.