Why should you write tests before writing code?

1 What is TDD?

TDD is a software development process that involves writing automated tests for a specific feature or functionality before writing the code that implements it. The tests define the expected behavior and outcome of the code, and act as a guide and a feedback mechanism for the developer. The tests also serve as a documentation and a validation tool for the code.

2 How does TDD work?

TDD follows a simple cycle of three steps: red, green, and refactor. First, you write a test that fails (red) because the code does not exist or does not meet the requirements. Then, you write the minimum amount of code that makes the test pass (green) without worrying too much about the quality or the design. Finally, you improve the code by refactoring (modifying) it to make it more readable, maintainable, and extensible, without changing its functionality or breaking the tests.

3 What are the benefits of TDD?

TDD can bring many advantages to your software development projects, such as clarifying your requirements and specifications before writing code, designing code in a modular and decoupled way, writing cleaner and simpler code, ensuring that your code works as intended, creating a comprehensive and reliable test suite, and developing faster with more confidence. It can save you time and avoid errors and misunderstandings, make it easier to reuse, modify, and extend your code, reduce complexity and bugs, meet the expectations of the users and stakeholders, serve as a safety net and documentation for your code, and get immediate feedback from tests.

4 What are the challenges of TDD?

TDD is not a magical solution to all your software development problems; it also has some challenges and drawbacks. It requires a mindset shift and discipline to write tests first and follow the cycle consistently, which can be difficult to adopt and maintain. Additionally, it requires knowledge and skill in writing effective and meaningful tests, as well as a suitable testing framework and tooling that varies depending on the language, platform, and domain of your project. Furthermore, TDD can increase the initial development time and effort as you have to write more code and tests upfront, which can be viewed as a waste or a delay by some developers and teams.

5 How can you start with TDD?

If you want to start with TDD, here are some tips and best practices that can help you. Begin by choosing a simple feature or functionality that you can test and implement easily, and practice the cycle of red, green, and refactor until you feel comfortable. Make sure your tests are focused, readable, and expressive, and that they test one thing at a time. Don't over-engineer or anticipate future needs; only write the code that satisfies the current test and the current requirements. Refactoring is essential to improve code quality and maintainability; however, be careful not to introduce new functionality or break existing tests when refactoring. Review your tests and code regularly, seek feedback from your peers, users, and stakeholders, and use it to refine your requirements and specifications. Learn from your mistakes and successes, and adapt your process and practices accordingly.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?