Automation Code Defect Density
Automation code defect density measures the number of defects found in automated test code relative to its size, helping evaluate the quality of test automation assets.
“Defect density of a component of the test automation code.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Automation Code Defect Density?
This metric helps teams assess the maintainability and reliability of automation scripts by identifying how frequently defects occur within the automation codebase.
Quality metric: Measures defects in test automation code rather than the application under test.
Maintainability: Lower defect density generally indicates higher-quality automation code.
Continuous improvement: Tracking trends helps improve automation practices over time.
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. Automation code defect density 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 Automation code defect density connects tests to the implementation structure where certain defects can hide.
Practice Questions
Question 1
Which interpretation of rising automation code defect density is MOST appropriate?
Question 2
Which action BEST reduces automation defect density over time?
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