To determine the percentage of decision testing coverage achieved by the given suite of test cases, we need to analyze the decisions and outcomes in the provided logic.
Detailed Analysis
* Identify all decisions in the logic:
* IF account number is valid
* IF customer account is active
* IF oldBalance < zero
* IF balance now >= zero
* IF account holder is VIP customer
* Calculate the number of unique decisions:
* There are 5 unique decision points in the logic.
* Determine the possible outcomes for each decision:
* IF account number is valid 2 outcomes (True, False)
* IF customer account is active 2 outcomes (True, False)
* IF oldBalance < zero 2 outcomes (True, False)
* IF balance now >= zero 2 outcomes (True, False)
* IF account holder is VIP customer 2 outcomes (True, False)
Test Cases Analysis
Test Case A
* Account number valid True
* Account is active True
* OldBalance = -100 True (less than zero)
* Balance now = +200 True (greater than zero)
* Not a VIP customer False
Test Case B
* Account number valid True
* Account is active True
* OldBalance = -100 True (less than zero)
* Balance now = -50 False (less than zero)
* Is a VIP customer True
Coverage Calculation
To calculate the decision coverage, we need to see how many of the possible outcomes are covered by the test cases:
* IF account number is valid (True in both A and B, False not tested)
* IF customer account is active (True in both A and B, False not tested)
* IF oldBalance < zero (True in both A and B, False not tested)
* IF balance now >= zero (True in A, False in B, both outcomes tested)
* IF account holder is VIP customer (False in A, True in B, both outcomes tested) Out of the 10 possible outcomes (2 for each decision), the given test cases cover 6 outcomes:
* Account number valid True
* Account number valid False (not covered)
* Customer account active True
* Customer account active False (not covered)
* OldBalance < zero True
* OldBalance < zero False (not covered)
* Balance now >= zero True
* Balance now >= zero False
* Account holder is VIP True
* Account holder is VIP False
Thus, 6 out of the 10 outcomes are covered by the test cases, giving us a decision coverage percentage of:
Decision Coverage=(610)×100%=60%\text{Decision Coverage} = \left(\frac{6}{10}\right) \times 100\% =
60\%Decision Coverage=(106)×100%=60%
References:
* The sample questions and answers provided in the ISTQB CTAL-TTA documentation confirm this calculation method and the expected coverage percentage for similar logical scenarios.