ISTQB Black-Box Test Design 2 — Questions and Answers
Question 1: Which black-box technique is most appropriate when testing a field that accepts values from 1 to 100, where behavior changes only at the boundaries?
- Decision table testing
- Boundary value analysis (Correct answer)
- State transition testing
- Use case testing
Correct answer: Boundary value analysis
Boundary value analysis targets the values at and just outside the limits (0, 1, 100, 101) where defects are most likely.
Question 2: In equivalence partitioning, what is the minimum number of test cases typically needed to cover a valid partition?
- One test case per partition boundary
- Two test cases per partition
- One representative test case per partition (Correct answer)
- Three test cases per partition
Correct answer: One representative test case per partition
EP assumes all values in a partition behave identically, so one representative value per partition is sufficient.
Question 3: A login system locks an account after 3 failed attempts and unlocks it after a successful admin reset. Which technique BEST models this behavior?
- Equivalence partitioning
- Cause-effect graphing
- State transition testing (Correct answer)
- Boundary value analysis
Correct answer: State transition testing
State transition testing models systems where outputs depend on current state and input, such as account locking workflows.
Question 4: A decision table has 3 conditions, each with 2 possible values. How many rule columns does a full decision table have?
- 6
- 8 (Correct answer)
- 9
- 12
Correct answer: 8
A full decision table has 2^n columns where n is the number of binary conditions, so 2^3 = 8.
Question 5: Which black-box technique focuses on the interactions between actors and the system to achieve a specific goal?
- Decision table testing
- Use case testing (Correct answer)
- Boundary value analysis
- Exploratory testing
Correct answer: Use case testing
Use case testing derives tests from use cases that describe goal-oriented interactions between actors and the system.
Question 6: When applying 2-value BVA to a numeric field accepting integers from 10 to 20, which set of test values is correct?
- 9, 10, 20, 21 (Correct answer)
- 10, 15, 20
- 9, 11, 19, 21
- 10, 20
Correct answer: 9, 10, 20, 21
2-value BVA tests the boundary values themselves and the values just outside: 9 (invalid), 10 (valid min), 20 (valid max), 21 (invalid).
Question 7: In a state transition diagram, what does a transition label typically consist of?
- State name and exit action
- Event and optional guard condition or action (Correct answer)
- Input value and expected output
- Test case ID and priority
Correct answer: Event and optional guard condition or action
Transition labels show the triggering event, an optional guard condition (in brackets), and an optional action (after a slash).
ISTQB Black-Box Test Design 2
Which black-box technique is most appropriate when testing a field that accepts values from 1 to 100, where behavior changes only at the boundaries?