What is "test-driven development" (TDD)?

Test-driven development (TDD) is fundamentally an agile development approach that emphasizes the practice of writing tests for a piece of functionality before actually writing the code that implements that functionality. This technique promotes a cycle of continuously improving software quality and ensuring that new code does not break existing functionalities.

In TDD, the typical workflow consists of the following steps:

1. Write a Test: Before any code is created, you define a test that specifies a function or improvement that is expected from the code. This test will initially fail, as there is no implementation yet.

2. Run the Test: Running the test at this point should yield a failure, confirming that the test is valid since the functionality it tests does not exist.

3. Implement the Code: Write the minimal amount of code necessary to pass the test. This encourages simplicity and fosters focused development.

4. Run the Test Again: After the implementation, the test is run again. If it passes, this confirms that the code meets the requirements defined in the test.

5. Refactor the Code: Finally, with the test passing, one can improve the code’s structure and maintainability while ensuring that the tests still pass.

By focusing