Atomic Condition
An atomic condition is a single logical condition that cannot be divided into smaller logical expressions within a decision.
“A condition that does not contain logical operators.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Atomic Condition?
Atomic conditions are the basic building blocks of logical decisions and are commonly referenced in white-box testing techniques such as condition testing and modified condition/decision coverage (MC/DC).
Logical building block: Each atomic condition evaluates independently as true or false.
Role in testing: Coverage techniques evaluate combinations of atomic conditions.
Code quality: Understanding atomic conditions improves decision testing effectiveness.
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. Atomic condition 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 Atomic condition makes hidden rule combinations visible before customers start cancelling trips.
Practice Questions
Question 1
Which is an atomic condition in decision 'isAdult && isMember'?
Question 2
Which test set MOST helps achieve MC/DC on 'A || (B && C)'?
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