The TDD Cycle: Red, Green, Refactor

Test-Driven Development (TDD) follows a repetitive cycle consisting of three phases: Red, Green, and Refactor. Each phase plays a vital role in the development process. Here's a closer look at what happens in each phase:

Red Phase

In the Red phase, a failing test is written. This means that a test is created to check for a specific behavior or functionality that has not been implemented yet. The test is expected to fail initially because there is no corresponding production code in place. This phase ensures that the developer has a clear understanding of what needs to be done.

Green Phase

In the Green phase, the focus shifts to implementing the code necessary to make the previously failing test pass. The goal is to write the minimum amount of code required to meet the test's requirements. This phase involves crafting the production code that satisfies the test's criteria, resulting in a passing test.

Refactor Phase

The Refactor phase follows the Green phase. During this phase, the code is improved without altering its behavior. Refactoring is essential for maintaining the quality and readability of the codebase. Developers can make changes to the code's structure, eliminate duplication, enhance naming conventions, and apply various refactoring techniques to improve the code's design and maintainability.

The TDD cycle is iterative, meaning it repeats continuously. After the Refactor phase, the process returns to the Red phase to write the next failing test. This iterative approach ensures that the codebase evolves incrementally. Each cycle adds new functionality and enhances the overall quality of the code.

In summary, the TDD cycle of Red, Green, Refactor is a powerful practice for building robust, maintainable software. By following this cycle, developers can systematically develop code that meets specific requirements, remains efficient, and is easy to maintain.