Desirable Characteristics of a Unit Test

Unit testing is a critical practice in software development that ensures individual components of the software function as intended. For unit tests to be effective, they should possess certain characteristics that enhance their reliability, speed, and maintainability.

Exam Question

Choose four desirable characteristics of a unit test.
(choose the best four answers)
A. Makes assertions about only one logical concept.
B. Execution is fast.
C. Test code is as small as possible.
D. Independent of others.
E. Includes exercising the persistence layer.

Correct Answers

A. Makes assertions about only one logical concept.
B. Execution is fast.
C. Test code is as small as possible.
D. Independent of others.

Explanation

Correct Answers

A. Makes assertions about only one logical concept:
A good unit test focuses on a single logical concept or behavior. By isolating a specific aspect of the code, it becomes easier to pinpoint the source of any issues, making the tests more reliable and easier to debug.

B. Execution is fast:
Unit tests should be quick to run. Fast execution encourages developers to run the tests frequently, which leads to quicker feedback and a more efficient development process.

C. Test code is as small as possible:
Unit tests should be concise and to the point. Smaller test code reduces complexity, makes the tests easier to understand, and minimizes maintenance efforts.

D. Independent of others:
Each unit test should be independent of other tests. This independence ensures that tests do not affect one another, leading to more accurate and reliable test results. It also allows tests to be run in any order.

Why the Other Option Is Less Appropriate

E. Includes exercising the persistence layer:
While testing the persistence layer is important, this is generally not the focus of a unit test. Unit tests are meant to test small, isolated pieces of functionality, typically without dependencies on external systems like databases. Testing the persistence layer is more suited to integration tests, where the interaction between multiple components can be verified.

Relevance to the PSD Exam

Understanding the characteristics of effective unit tests is essential for the PSD exam. It underscores the importance of writing reliable, maintainable, and efficient tests that can be run frequently to ensure code quality.

Key Takeaways

• Focused tests on a single logical concept make debugging easier.
• Fast execution encourages frequent testing and quick feedback.
• Small test code is easier to understand and maintain.
• Independence of tests ensures reliability and accurate results.

Conclusion

Unit tests are a fundamental part of ensuring code quality in software development. By focusing on single concepts, executing quickly, maintaining small and independent test code, developers can create a robust test suite that supports efficient and effective software development. For more information on preparing for the PSD exam, visit our Professional Scrum Developer PSD™ Exam Prep.