White-box Test Technique
A white-box test technique is a test design technique that derives test cases from the internal structure, implementation, or code of a software system.
“A test technique based on the internal structure of a component or system.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is White-box Test Technique?
These techniques measure structural coverage and verify that important code elements such as statements, branches, conditions, and paths have been exercised.
Code based: Requires knowledge of the internal implementation.
Structural coverage: Measures executed program structures.
Developer focused: Commonly applied during component testing.
Real World Example
A tax calculation module applies different deductions depending on income band, residency status, and submitted documents.
Reviewing the final tax amount is not enough when important code paths may never execute during testing. White-box test technique helps the tester reason about the structure behind the result.
The tester works with the developer to identify decisions or paths in the calculation logic and designs inputs that exercise the meaningful alternatives.
The team gains better evidence about hidden logic because White-box test technique connects tests to the implementation structure where certain defects can hide.
Practice Questions
Question 1
Which statement BEST describes White-box test technique in the context of ISTQB terminology?
Question 2
A tester needs to explain White-box test technique to a non‑technical stakeholder. Which approach is MOST appropriate?
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