Explain the three steps of the TDD cycle in Python

TDD Cycle: Red-Green-Refactor and the purpose of each step

The Test-Driven Development (TDD) cycle consists of three main steps, often referred to as the "Red-Green-Refactor" cycle. These steps are repeated for each new feature or code modification in the TDD approach. The three steps are:

Red: Write a Failing Test (Red Phase).

• In the Red phase, developers start by writing a test that describes the desired behavior of the code they want to implement.
• The test is intentionally written to fail if the desired functionality does not exist yet.
• This failing test is often referred to as a "red" test because it signals that the code does not yet meet the specified requirements.

Green: Write the Minimum Code to Pass (Green Phase).

• In the Green phase, developers write the minimum amount of code necessary to make the failing test pass (i.e., turn it "green").
• The primary goal is to make the test case pass as quickly as possible without focusing on writing the most efficient or complete implementation.
• The code written during this phase may be straightforward and not optimized, but it should produce the correct output for the given input.

Refactor: Improve the Code without Changing Behavior (Refactor Phase)

• In the Refactor phase, developers improve the code and test cases without changing the code's behavior.
• This phase optimizes the code, removes duplication, and makes it more maintainable. This is without introducing new functionality or changing existing behavior.
• The tests ensured that the refactoring did not introduce regressions or unintended side effects.

The Purpose of Each Step in the Red-Green-Refactor Cycle:

Red (Write a Failing Test):

• The Red phase starts by writing a failing test that describes the desired behavior of the code.
• The failing test acts as a specification for the code to be implemented, outlining what it should do when complete.
• By writing the test first, developers have a clear goal of what they need to achieve before implementing the actual code.

Green (Write the Minimum Code to Pass):

• The purpose of the Green phase is to write the minimum amount of code required to make the failing test pass successfully.
• The focus is on getting the test to pass, without worrying about optimization or completeness at this stage.
• This step encourages developers to write simple, straightforward code that meets immediate requirements.

Refactor (Improve the Code without Changing Behavior):

• The Refactor phase improves code's design, organization, and efficiency without altering its functionality.
• Developers can safely restructure code, remove duplications, and make it more maintainable. They know that if any issues arise, the tests will catch them.
• This step ensures that the codebase evolves over time, continuously improving its quality and readability.