Effective Strategies for Refactoring Legacy Code with Unit Tests

16 July 2024 Stephan Petzl Leave a comment QA

Refactoring legacy code can be a daunting task, especially when there are unclear boundaries between components. Ensuring that no new issues are introduced during the refactoring process is essential. This guide provides a structured approach to refactoring your code while maintaining its integrity through unit tests.

Steps to Refactor Legacy Code Using Unit Tests

Here’s a step-by-step approach to help you refactor your legacy code effectively:

1. Create Unit Tests Before Refactoring: Before making any changes, write unit tests for the existing code. This ensures that you have a known state of your code and can detect if any issues arise due to the refactoring.
2. Run Unit Tests: Execute the unit tests to ensure they pass. This validates that your tests correctly reflect the current functionality of the code.
3. Refactor the Code: Make the necessary changes to improve the code structure, readability, and maintainability.
4. Re-run Unit Tests: After refactoring, run the unit tests again to verify that the changes did not break the existing functionality.

Additional Best Practices

To further streamline the refactoring process, consider the following best practices:

• Use Characterization Tests: Characterization tests help capture the current behavior of the legacy code. These tests ensure that the refactored code behaves consistently with the original code.
• Branching by Abstraction: Identify pinch points in your code where you can insert interfaces to abstract the inputs and outputs. This technique helps manage the transition from the old implementation to the new one seamlessly.
• Log Side Effects: For functions with side effects (e.g., changing global variables, databases, files), log these changes to understand their impact and ensure they are handled correctly during refactoring.

Recommended Reading

For a more in-depth understanding of refactoring legacy code and applying TDD principles, consider these books:

• Working Effectively with Legacy Code by Michael Feathers
• Brownfield Application Development in .NET by Kyle Baley and Donald Belcham

Leveraging No-Code Test Automation with Repeato

Refactoring and maintaining tests can be a time-consuming process, especially for complex applications. This is where Repeato, a No-Code Test Automation tool, can be highly beneficial. Repeato allows you to create, run, and maintain automated tests for iOS and Android apps effortlessly. Utilizing computer vision and AI, Repeato makes it particularly fast to edit and run tests, ensuring your refactoring efforts do not introduce new issues.

For more detailed information on utilizing virtual test devices, running test batches, and other advanced testing techniques, visit our documentation section.

By integrating Repeato into your testing workflow, you can ensure a smooth and efficient refactoring process, ultimately leading to higher quality and more maintainable code.

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