Introduction to Test Driven Development

Tutorial 5 of 5

Introduction

In this tutorial, we will introduce you to Test Driven Development (TDD), a modern software development approach where you write tests before writing the code. Our goal is to help you understand the fundamental principles of TDD and how it can lead to creating higher quality software with fewer bugs.

What You Will Learn

The fundamental principles of Test Driven Development
How to write tests before code
Importance of TDD and its benefits

Prerequisites

Basic knowledge of software development
Familiarity with a programming language. For this tutorial, we will be using JavaScript.

Step-by-Step Guide

Test Driven Development (TDD) is a software development approach in which tests are written before the actual code. The process is often described as "Red, Green, Refactor." Here's how it works:

Red: Write a test that fails.
Green: Write the minimum amount of code necessary to make the test pass.
Refactor: Clean up the code, while ensuring that tests still pass.

This cycle repeats throughout the code development process.

Best Practices and Tips

Write the simplest code to pass the test.
Only write new code when a test is failing.
Refactor code after the test is passing.

Code Examples

Example 1: Basic TDD Cycle

Let's say we want to develop a function to add two numbers. Here's how we might do it with TDD.

Test

const assert = require('assert');
const add = require('./add');

assert.equal(add(1, 2), 3);

This test will initially fail because we haven't written the add function yet.

Code

Now we write the simplest code to pass the test.

function add(a, b) {
    return a + b;
}

module.exports = add;

Summary

In this tutorial, we covered the basics of Test Driven Development (TDD), including its fundamental principles, writing tests before code, and the benefits of using TDD. We also went through a basic example of the TDD cycle: writing a failing test, writing code to pass the test, and then refactoring the code.

Practice Exercises

To further understand TDD, try these exercises:

Write a function to subtract two numbers using TDD.
Write a function to multiply two numbers using TDD.

Remember to follow the TDD cycle: write a failing test, write code to pass the test, and then refactor the code.

Additional Resources

Keep practicing TDD in your projects, and you'll soon see the benefits it brings to your code quality!