The basic cycle of TDD is: Decide on a small piece of functionality you want to add. Write a test that will pass once that functionality is implemented. Run all tests. Verify that the only failure is the one you just wrote. Write the smallest amount of code needed to get the test to pass, and verify that the tests now run cleanly. Refactor your code: see if there is a way to improve on what you just wrote (the test or the function). Make sure the tests still pass when you’re done.
