Condition Coverage
Condition coverage is a white-box coverage metric that measures whether every individual condition within a decision has evaluated to both true and false during testing.
“The coverage of condition outcomes.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Condition Coverage?
Condition coverage focuses on the Boolean expressions that make up decisions, ensuring each condition independently produces both outcomes at least once.
Individual conditions: Each Boolean condition is measured separately.
Coverage objective: Every condition should evaluate to true and false.
Relationship to branch coverage: Full branch coverage does not always guarantee full condition coverage.
Real World Example
A travel platform is changing its refund policy for cancelled flights, with different outcomes depending on ticket type, cancellation time, loyalty status, and airline disruption reason.
No single happy-path test can cover the combinations. Condition coverage helps the tester see which conditions must be varied together and which outcomes should result.
The tester maps the policy into compact rules, removes impossible combinations, and designs cases that prove each meaningful refund decision is handled correctly.
The team avoids contradictory refund behavior because Condition coverage makes hidden rule combinations visible before customers start cancelling trips.
Practice Questions
Question 1
Which set improves condition coverage for A && B?
Question 2
Why might 100% branch still miss issues?
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