Test-driven development

Now that we have our tests written, how can they be integrated into the development process? Currently, we are using our tests in order to ensure code correctness after we create some feature. But, what if we flipped the order and used tests in order to create correct code from the beginning? This is what test-driven development (TDD) advocates.

TDD follows a simple loop to write the code of a new feature in your application:

Credit for this image goes to user Excirial on Wikipedia

In a project that uses TDD, the first thing that you write, before any of the code that controls what you are actually building, is the tests. What this forces the programmers on the project to do is to plan out the project's scope, design, and requirements before writing any code. While designing APIs, it also forces the programmer to design the interface of the API from a consumer's perspective rather than design the interface after all the backend code has been written.

In TDD, tests are...