ISTQB White-Box Test Design 2 — Questions and Answers
Question 1: Which coverage criterion requires that every loop in the code is executed at least once with zero iterations, one iteration, and multiple iterations?
- Statement coverage
- Branch coverage
- Loop coverage (Correct answer)
- Path coverage
Correct answer: Loop coverage
Loop coverage specifically targets loop constructs by requiring execution with zero, one, and multiple iterations to reveal off-by-one and boundary errors.
Question 2: A developer has written a function with 5 independent conditions in a single compound predicate. How many test cases are needed for Modified Condition/Decision Coverage (MC/DC)?
- 32
- 10
- 6 (Correct answer)
- 16
Correct answer: 6
MC/DC requires N+1 test cases for N independent conditions, so 5 conditions require 6 test cases.
Question 3: In control flow testing, what is a 'predicate' node?
- A node that represents a function call
- A node where the flow splits based on a condition (Correct answer)
- A node that merges two execution paths
- A node representing a variable assignment
Correct answer: A node where the flow splits based on a condition
A predicate node is a decision point in the control flow graph where execution can follow different paths based on a Boolean condition.
Question 4: Which white-box technique is MOST suitable for testing code that contains nested if-else structures with complex boolean expressions?
- Statement coverage
- Decision coverage
- MC/DC coverage (Correct answer)
- Data flow coverage
Correct answer: MC/DC coverage
MC/DC is specifically designed to independently test each condition within complex Boolean expressions, making it ideal for nested conditionals.
Question 5: A tester achieves 100% statement coverage on a module. What can they conclude?
- All branches have been tested
- All paths have been tested
- Every executable statement was executed at least once (Correct answer)
- All conditions evaluated to both true and false
Correct answer: Every executable statement was executed at least once
100% statement coverage only guarantees every executable statement was executed at least once; branches and paths may remain untested.
Question 6: In data flow testing, a 'kill' (k-use) of a variable occurs when:
- The variable is assigned a new value, overwriting the previous one (Correct answer)
- The variable is read inside a predicate
- The variable is used in a computation
- The variable is passed as a parameter
Correct answer: The variable is assigned a new value, overwriting the previous one
A kill or definition-kill occurs when a variable is re-defined or assigned a new value, terminating the previous definition's reach.
Question 7: Which metric is used to estimate the minimum number of independent paths in a program and thus the minimum test cases for path coverage?
- Lines of code
- Cyclomatic complexity (Correct answer)
- Fan-out number
- Halstead volume
Correct answer: Cyclomatic complexity
Cyclomatic complexity (V(G) = E - N + 2P) gives the number of linearly independent paths through the code.
ISTQB White-Box Test Design 2
Which coverage criterion requires that every loop in the code is executed at least once with zero iterations, one iteration, and multiple iterations?