Understanding Code Quality Metrics

Code quality metrics are crucial for assessing the maintainability, complexity, and overall quality of a codebase. These metrics help developers identify potential areas for improvement and ensure that the software is reliable and easy to maintain.

Exam Question

Which three of the following are code quality metrics?
(choose the best three answers)
A. Class coupling.
B. Cycle time per Product Backlog Item.
C. Unit tests per class.
D. Number of check-ins per day.
E. Cyclomatic complexity.
F. Depth of inheritance.

Correct Answers

A. Class coupling.
E. Cyclomatic complexity.
F. Depth of inheritance.

Explanation

Correct Answers

A. Class coupling:
Class coupling measures the level of interdependence between classes or modules in a codebase. High coupling can make the code more difficult to maintain and refactor, as changes in one class may affect others. Low coupling is generally preferred, as it indicates a more modular and maintainable codebase.

E. Cyclomatic complexity:
Cyclomatic complexity is a metric that measures the complexity of a program by counting the number of linearly independent paths through the source code. Higher cyclomatic complexity indicates more complex and potentially harder-to-maintain code. This metric is used to assess the risk of errors and the effort required to test the code.

F. Depth of inheritance:
Depth of inheritance measures the levels of inheritance in an object-oriented program. A deeper inheritance hierarchy can make the code more difficult to understand and maintain, as it may require navigating through multiple levels of inheritance to understand the behavior of a class.

Why the Other Options Are Less Appropriate

B. Cycle time per Product Backlog Item:
This is a flow metric related to process efficiency, not directly a code quality metric. It measures how long it takes to complete a Product Backlog item but does not assess the quality of the code itself.

C. Unit tests per class:
While important for ensuring that code is well-tested, this metric does not directly measure the quality of the code itself. It is more of an indicator of test coverage.

D. Number of check-ins per day:
This is a metric related to development activity, not code quality. Frequent check-ins can indicate active development but do not directly reflect the quality of the code.

Relevance to the PSD Exam

Understanding code quality metrics is essential for the PSD exam, as these metrics help ensure that the code is maintainable, reliable, and easy to understand. They are critical tools for developers to assess and improve the quality of their code.

Key Takeaways

• Class coupling measures the interdependence between classes, affecting maintainability.
• Cyclomatic complexity measures the complexity of the code, influencing its readability, testability, and maintainability.
• Depth of inheritance assesses the complexity introduced by inheritance hierarchies, impacting the ease of understanding and maintaining the code.

Conclusion

Code quality metrics like class coupling, cyclomatic complexity, and depth of inheritance are vital for maintaining a high-quality codebase. These metrics help developers identify areas that may need refactoring or additional testing to ensure long-term maintainability and reliability. For more information on preparing for the PSD exam, visit our Professional Scrum Developer PSD™ Exam Prep.