Understanding Test-Driven Development (TDD)

Test-Driven Development (TDD) is a software development practice where developers write a test before writing the code that needs to pass the test. This practice ensures that the code meets the requirements and is working as expected.

Exam Question

While practicing Test-Driven Development, what is done after the test fails?
(choose the best answer)
A. Refactor the test so the code passes.
B. Run it again to make sure it really fails.
C. Meet with the business analyst to ensure that the test is correct.
D. Write the minimum amount of product code to satisfy the test.
E. Implement the required functionality.

Correct Answer

D. Write the minimum amount of product code to satisfy the test.

Explanation

Correct Answer

D. Write the minimum amount of product code to satisfy the test:
In Test-Driven Development (TDD), the process begins with writing a test that defines a new function or improvement. When this test is run, it should fail because the functionality has not been implemented yet. The next step is to write the minimum amount of code necessary to make the test pass. The idea is to focus on getting the test to pass with as little code as possible, ensuring that the codebase remains simple and only does what is required to meet the test.

Why the Other Options Are Less Appropriate

A. Refactor the test so the code passes:
Refactoring the test to make it pass is not the correct approach. The purpose of TDD is to ensure that the code meets the predefined requirements as expressed by the test. Changing the test to fit the code defeats the purpose of TDD.

B. Run it again to make sure it really fails:
While it is important to ensure that the test fails initially (to confirm that the test is working), the next step after confirming the failure is to write code to make the test pass, not simply running it again.

C. Meet with the business analyst to ensure that the test is correct:
While collaboration with business analysts is important, in the context of TDD, the developer’s immediate next step after a test fails is to write the necessary code to pass the test, not to consult with others unless the test is incorrect.

E. Implement the required functionality:
This option is close but not entirely accurate in the context of TDD. The focus in TDD is on writing just enough code to pass the test, rather than implementing the entire functionality all at once.

Relevance to the PSD Exam

Understanding the steps involved in Test-Driven Development is crucial for the PSD exam. It ensures that developers follow best practices in writing clean, efficient, and testable code.

Key Takeaways

• After a test fails in TDD, the developer should write the minimum amount of code required to pass the test.
• TDD encourages writing tests before the implementation, focusing on small, incremental changes to the codebase.
• The goal is to keep the code simple and to ensure that it only does what is necessary to satisfy the test.

Conclusion

Test-Driven Development (TDD) is an essential practice in Agile and Scrum, helping developers ensure that their code meets the required functionality in the simplest way possible. Understanding the correct sequence of steps in TDD is vital for effective software development. For more information on preparing for the PSD exam, visit our Professional Scrum Developer PSD™ Exam Prep.