Stub
A stub is a test double that replaces a called software component during testing by providing predefined responses.
“A type of test double providing predefined responses.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Stub?
Stubs allow testing of a component even when dependent modules are unavailable, incomplete, or difficult to access.
Dependency replacement: Simulates called components.
Predefined behavior: Returns fixed responses.
Isolation: Enables independent component testing.
Real World Example
A regulated product team is preparing a release where Stub appears in reviews, test design conversations, or defect triage rather than as an isolated glossary word.
The risk is that the team treats Stub as interchangeable with nearby ISTQB terms. That makes test scope blurry and can lead to weak evidence for the release decision.
The tester anchors the discussion in the official definition, asks where the concept appears in the product, and designs examples that show the difference between Stub and similar ideas.
The page becomes useful in practice because Stub is connected to a specific testing decision, not memorized as a detached definition.
Practice Questions
Question 1
Which statement BEST describes Stub in the context of ISTQB terminology?
Question 2
A tester needs to explain Stub to a non‑technical stakeholder. Which approach is MOST appropriate?
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