CTAL-TTA Exam Dumps : Certified Tester Advanced Level Technical Test Analyst

In the context of software testing, different safety integrity levels (SIL) require different levels of rigor in testing. According to the IEC61508 standard, for software components rated at SIL 2, achieving 100% statement coverage and 100% decision coverage is recommended. Statement coverage ensures that every line of code is executed at least once during testing, while decision coverage ensures that every decision in the code (e.g., every branch of an IF statement) is executed on both the true and false sides. These coverage criteria ensure a thorough testing of the software components to validate that they behave correctly in all circumstances. Multiple condition coverage and MC/DC coverage (Options A and B) are more rigorous and typically required for higher SIL levels, such as SIL 4.

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​​​​​​.

API testing tends to focus on individual inputs more than combinations of inputs. This is because APIs, as the intermediary layers of software, often handle specific types of data input and output rather than user interaction sequences. GUI testing, on the other hand, involves testing the interface with which the user interacts, which frequently includes testing various combinations of user inputs and sequences to simulate actual user scenarios. Thus, GUI testing typically requires checking the integration and behavior of elements in combination to ensure they work together as expected in a user environment .