Decision tables
A checkout's rules depend on these conditions, and every combination of them can happen.
- Coupon: Valid, Expired, None
- Express delivery: Yes, No
- First order: Yes, No
Practice · Test design
Decision table testing questions and answers
Exam-style decision tables questions, generated fresh each time, with answers computed to the ISTQB Foundation Level v4.0 definitions (section 4.2.3). Every wrong answer tells you which mistake leads to it.
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What the syllabus asks for
A decision table lists conditions as rows and combinations of their values as columns, with the resulting actions below. A full table has a column for every combination, so the number of columns is the product of the number of values each condition can take.
The coverage items are the columns that contain feasible combinations. 100% decision table coverage means every one of those columns has been exercised by a test.
Worked examples
Example 1
A checkout's rules depend on these conditions, and every combination of them can happen.
- Coupon: Valid, Expired, None
- Member: Yes, No
- First order: Yes, No
How many columns does the full decision table have?
- A. 7
- B. 8
- C. 24
- D. 12
Show the answer
Answer: 12. A full table has a column for every combination: 3 × 2 × 2 = 12.
- 7: That adds the values up. A full table has a column for every combination, so the counts multiply.
- 8: That is 2 to the power of the number of conditions, which is right only when every condition is yes/no.
- 24: That doubles the table, as if there were one more yes/no condition.
Try this one in the quiz: open example 1.
Example 2
A checkout's rules depend on these conditions. Only members can choose to pay by invoice: a guest paying by invoice can't happen.
- Payment: Card, PayPal, Invoice
- Express delivery: Yes, No
- Member: Yes, No
- First order: Yes, No
How many coverage items does decision table testing identify, once the infeasible columns are removed?
- A. 24
- B. 20
- C. 23
- D. 16
Show the answer
Answer: 20. The full table has 3 × 2 × 2 × 2 = 24 columns. A guest paying by invoice is 1 of the 2 × 3 = 6 combinations of those two conditions, so 4 of the 24 columns are infeasible. 20 remain.
- 24: That is the full table. The coverage items are only the columns that can happen, so the guest-and-invoice columns are removed.
- 23: That removes one column. Guest and invoice together are impossible whatever the other conditions are, so every column with that pair goes.
- 16: That treats every condition as yes/no. A condition with three values triples the columns, it doesn't double them.
Try this one in the quiz: open example 2.
Example 3
A checkout's rules depend on these conditions, and every combination of them can happen.
- Express delivery: Yes, No
- Order total over 50: Yes, No
- Payment: Card, PayPal, Invoice
How many columns does the full decision table have?
- A. 24
- B. 8
- C. 12
- D. 7
Show the answer
Answer: 12. A full table has a column for every combination: 2 × 2 × 3 = 12.
- 24: That doubles the table, as if there were one more yes/no condition.
- 8: That is 2 to the power of the number of conditions, which is right only when every condition is yes/no.
- 7: That adds the values up. A full table has a column for every combination, so the counts multiply.
Try this one in the quiz: open example 3.
What this is not
These are not questions from any ISTQB exam, and this site has no connection with ISTQB or any exam provider. Older question banks often use definitions from before version 4.0, so if an answer here disagrees with one you’ve seen elsewhere, check which syllabus it was written for. How the questions are made explains how every answer is checked.
To see the technique applied, read the decision table generator.