What is test-driven development (TDD)?

Test-Driven Development (TDD) is a software development methodology that emphasizes the creation of tests before writing the actual code for a software application or system. This approach flips the traditional development model on its head, which typically involves writing code first and then creating tests afterward to check its functionality. Here’s how TDD works:

1. Write a Test: Before writing functional code, the developer writes an automated test case for a new function or improvement. This test is designed to fail initially, as the code it is testing does not yet exist.

2. Run the Test: The developer runs the test to ensure that it fails. This step confirms that the test is correctly set up and that it requires a new piece of code to pass. It also ensures that the test truly verifies the functionality it is intended to test.

3. Write the Code: With the failing test in place, the developer then writes just enough code to pass the test. The goal here is not to craft a fully featured implementation on the first try but to take small steps towards meeting the test’s requirements.

4. Run Tests Again: After writing the initial code, the developer runs all tests again. This includes the new test, which should now pass, as well as any existing tests, to ensure that the new code has not broken anything that was previously working.

5. Refactor: With all tests passing, the developer can then clean up the code, confident that changes and optimizations will not break