Writing Unit Testable Code: Best Practices and Guidelines

Writing Unit Testable Code: Best Practices and Guidelines

21 May 2024 Stephan Petzl Leave a comment Tech-Help

Creating unit testable code is essential for maintaining robust, changeable, and maintainable software. This article provides practical guidelines to help you write code that is easier to unit test, drawing from established best practices in the industry.

Key Practices for Writing Unit Testable Code

1. Test-Driven Development (TDD)

Adopting TDD means writing your tests before the actual code. This approach forces you to think about the testability of your code from the outset and helps ensure that you only write code that is necessary. TDD also promotes a more modular design, making your code easier to test.

2. Dependency Injection

Dependency injection is a technique where an object receives other objects it depends on, rather than creating them internally. This makes it easier to substitute real objects with mock objects during testing. Implementing dependency injection can significantly enhance the testability of your code.

3. Refactor to Interfaces

Programming to interfaces rather than concrete classes allows for greater flexibility and easier mocking during tests. By depending on interfaces, your classes become less tightly coupled, making it simpler to isolate and test individual components.

4. Smaller, More Targeted Methods

Breaking down your methods into smaller, more focused units makes them easier to test. Smaller methods reduce complexity and make it easier to write specific tests that target individual functionalities.

5. Avoid Static and Singleton Classes

Static and singleton classes can be challenging to mock and test due to their global state and lifecycle. Whenever possible, avoid using these patterns to maintain better testability.

6. Follow the Single Responsibility Principle

Ensure each class has a single responsibility. This principle simplifies your classes and makes them easier to test. A class with a single responsibility is more likely to be modular, reducing dependencies and increasing testability.

7. Make Public Methods Virtual

Making public methods virtual (if you are not using interfaces) allows you to override them in mock classes. This flexibility can be beneficial when you need to test different behaviors and interactions.

8. Avoid Sealed Classes

Sealed classes cannot be inherited, which can limit your ability to create mock versions for testing. Avoid using sealed classes unless absolutely necessary.

Additional Tips for Effective Unit Testing

1. DRY Principle

Follow the “Don’t Repeat Yourself” (DRY) principle by avoiding duplicate test data. Reuse test data across multiple tests to maintain consistency and reduce redundancy.

2. Code Reviews for Unit Tests

Incorporate unit tests into your code review process. This practice ensures that tests are well-written, comprehensive, and maintain the same quality standards as your production code.

3. Refactor Untestable Code

Spend time refactoring untestable code to make it more testable. Achieving high test coverage can help you identify potential issues early and improve the overall quality of your codebase.

Leveraging Repeato for Automated Testing

In the realm of mobile app development, maintaining testable code is crucial for ensuring high-quality releases. Repeato, our no-code test automation tool for iOS and Android, can significantly streamline this process. With Repeato, you can create, run, and maintain automated tests for your apps with ease.

Repeato’s intuitive test recorder and no-code interface allow even those with limited coding experience to set up robust tests quickly. For advanced testers, the scripting interface facilitates the automation of complex use cases. Additionally, Repeato supports website testing within Android emulators or devices, with explicit web testing support coming later this summer.

By incorporating Repeato into your testing workflow, you can ensure that your mobile apps are thoroughly tested, leading to more reliable and bug-free releases.

For more information on how to get started with Repeato, visit our documentation page.

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