Which of the following is the minimum number of test cases needed to cover the full decision table associated with this scenario?

A company wants to reward each of its salespeople with an annual bonus that represents the sum of all the bonuses accumulated for every single sale made by that salesperson. The bonus for a single sale can take on the following four values: 3%, 5%, 7% and 10% (the percentage refers to the amount of the single sale). These values are determined on the basis of the type of customer (classified as "Basic" or "Premium") to which such sale was made, and on the amount of such sale classified into the following three groups G1, G2 and G3:

• [G1]: less than 300 euros

• [G2]: between 300 and 2000 euros

• [G3]: greater than 2000 euros

Which of the following is the minimum number of test cases needed to cover the full decision table associated with this scenario?
A . 12
B . 6
C . 4
D . 3

View Answer

Answer: B

Explanation:

The minimum number of test cases needed to cover the full decision table associated with this scenario is 6. This is because the decision table has 4 conditions (type of customer and amount of sale) and 4 actions (bonus percentage). The conditions have 2 possible values each (Basic or Premium, and G1, G2 or G3), so the total number of combinations is 2 x 2 x 2 x 2 = 16. However, not all combinations are valid, as some of them are contradictory or impossible. For example, a sale cannot be both less than 300 euros and greater than 2000 euros at the same time. Therefore, we need to eliminate the invalid combinations and keep only the valid ones.

The valid combinations are:

These 6 combinations cover all the possible values of the conditions and actions, and they are the minimum number of test cases needed to cover the full decision table.

Reference: ISTQB Certified Tester Foundation Level (CTFL) v4.0 sources and documents,