Test Driven Development

As I progress more in my CS studies, I’m starting to move beyond learning how to write the code for a project to how the project should be designed overall. In fact, this is one of the main purposes of two of my current CS classes. This has lead me to learning about TDD, or Test Driven Development. I’ve come across a fantastic article by Andrea Koutifaris which outlines the concept well called Test Driven Development: what it is, and what it is not.

In this article, I’ve learned the purpose of writing test driven code and what the plan for doing it should be. In TDD, tests come first in the process while writing production code comes second. This is in order to almost put oneself in a user’s shoes. If I myself in the user, what do I want my code to do? This is where the tests come in. Once the goals are clear and defined, the production code can be written.

The rules for TDD can be broken down to two essential parts:

• “Write only enough of a unit test to fail”
• “Write only enough production code to make the failing unit test pass”

Tests must be written to be very specific and achieve the ultimate application goals. Analysis of your tests can help you determine a method to writing your production code. They often not only outline what need to be achieved, but how it needs to be achieved.

The next part of TDD would be writing production code. As outlined before, the second essential rule of TDD is to “Write only enough production code to make the failing test unit pass.” Had production code been written first, output may not match user goals and unnecessary code may be written, which comes with its own set of problems. The focus is on writing clean code and limiting the amount which you write.

The last part of TDD would be the “refractor phase.” This is where code can be changed to be better, but what is stressed here is removing all duplicate code and consolidating.

The result of TDD should be efficient, clean code which serves its purpose. Although it can seem long-winded and like extra work, it’s mostly just inverting the process which we usually work by, so once the process is learned and practiced, it can help with writing better code more coherently and more focused on user goals, which is the ultimate goal as a programmer.