ISTQB Black-Box Test Design 5 — Questions and Answers
Question 1: A vending machine dispenses items only when the balance equals or exceeds the price and an item is selected. This behavior is BEST modeled by which technique?
- Boundary value analysis
- Decision table testing (Correct answer)
- State transition testing
- Pairwise testing
Correct answer: Decision table testing
Decision table testing handles combinations of conditions (sufficient balance AND item selected) that jointly determine the outcome.
Question 2: Which of the following BEST describes the purpose of a state transition table compared to a state diagram?
- It shows the graphical flow between states
- It provides a tabular view that makes missing transitions easier to identify (Correct answer)
- It replaces the need for equivalence partitioning
- It documents the source code logic
Correct answer: It provides a tabular view that makes missing transitions easier to identify
A state transition table is a tabular representation that makes incomplete or missing transitions (impossible combinations) explicit and easier to identify.
Question 3: A tester discovers that a system behaves correctly for inputs within valid partitions but crashes for a value of 0 that was not explicitly identified as a boundary. What does this suggest?
- The equivalence partitions were correctly defined
- The test design missed an invalid equivalence class or boundary (Correct answer)
- Boundary value analysis was applied correctly
- The system has no defects
Correct answer: The test design missed an invalid equivalence class or boundary
The crash reveals that 0 was an unconsidered boundary or invalid partition that should have been included in the test design.
Question 4: Which term describes a pair of states connected by a transition in a state machine, used as the basis for 1-switch coverage?
- Transition pair (Correct answer)
- State sequence
- Sneak path
- Event chain
Correct answer: Transition pair
1-switch coverage requires exercising all valid sequences of two consecutive transitions (transition pairs) through intermediate states.
Question 5: When combining black-box techniques, which combination is MOST commonly used to test a numeric input field with distinct behavioral ranges?
- Decision table + state transition testing
- Equivalence partitioning + boundary value analysis (Correct answer)
- Use case testing + pairwise testing
- Cause-effect graphing + use case testing
Correct answer: Equivalence partitioning + boundary value analysis
EP identifies the distinct valid and invalid ranges, and BVA then tests the critical boundary values within and between those ranges.
Question 6: A decision table test designer collapses two rule columns because they produce the same action regardless of one condition's value. What is this called?
- Partition merging
- Rule consolidation using don't-care conditions (Correct answer)
- Equivalence reduction
- Boundary compression
Correct answer: Rule consolidation using don't-care conditions
When a condition's value does not affect the outcome, it is marked as a don't-care (–), allowing two columns to be merged into one.
Question 7: In ISTQB terminology, which black-box technique derives test cases from the ways users interact with the system to accomplish their objectives?
- Equivalence partitioning
- Boundary value analysis
- Decision table testing
- Use case testing (Correct answer)
Correct answer: Use case testing
Use case testing derives test cases from use cases, which describe the sequences of interactions between actors and the system to achieve goals.
ISTQB Black-Box Test Design 5
A vending machine dispenses items only when the balance equals or exceeds the price and an item is selected.
This behavior is BEST modeled by which technique?