Introduction

Tutorial's Goal

In this tutorial, we will cover the methodology of Test-Driven Development (TDD) and its implementation in Laravel projects. You will learn how to write tests before developing the actual code, which is an effective way to ensure the robustness and reliability of your application.

What You Will Learn

• Basics of Test-Driven Development (TDD)
• How to implement TDD in Laravel
• Writing and running tests

Prerequisites

• Basic knowledge of PHP and Laravel
• Familiarity with PHPUnit (the testing framework Laravel uses)

Step-by-Step Guide

TDD Concepts

Test-Driven Development (TDD) is a software development approach where you write tests before you write the actual code. The process involves three steps:

1. Red: Write a failing test.
2. Green: Write the minimum amount of code to make the test pass.
3. Refactor: Improve the code while ensuring the test still passes.

This approach ensures that your code does exactly what it's supposed to do.

Laravel Testing

Laravel is built with testing in mind. In fact, support for testing with PHPUnit is included out of the box, and a phpunit.xml file is already set up for your application. The framework also ships with convenient helper methods allowing for expressive testing of your applications.

Code Examples

Example 1: Basic Test

In Laravel, all tests are stored in the tests directory. Let's create a simple test to check if our application's main page loads correctly.

// tests/Feature/ExampleTest.php

namespace Tests\Feature;

use Tests\TestCase;

class ExampleTest extends TestCase
{
    /** @test */
    public function main_page_loads_correctly()
    {
        $response = $this->get('/');

        $response->assertStatus(200);
    }
}

This test uses Laravel's HTTP tests feature. We are sending a GET request to the application's main page (/) and asserting that the HTTP status is 200, meaning the page loaded correctly.

Example 2: Testing a Model

Let's write a test for a hypothetical User model in our application. We want to ensure that when a new user is created, the user count increases by one.

// tests/Unit/UserTest.php

namespace Tests\Unit;

use App\Models\User;
use Illuminate\Foundation\Testing\RefreshDatabase;
use Tests\TestCase;

class UserTest extends TestCase
{
    use RefreshDatabase;

    /** @test */
    public function a_user_can_be_created()
    {
        User::factory()->create();

        $this->assertCount(1, User::all());
    }
}

Here, we're using Laravel's model factories and database testing traits. RefreshDatabase will roll back any database changes after each test, ensuring a fresh state.

Summary

In this tutorial, you learned the basics of Test-Driven Development (TDD) and how to implement it in Laravel. You learned how to write tests using PHPUnit and Laravel's convenient testing tools.

Next Steps

Continue practicing TDD in your Laravel projects. Try to write tests for different parts of your application, like controllers, middleware, and so on.

Additional Resources

• PHPUnit Documentation
• Laravel Testing Documentation

Practice Exercises

1. Write a test to verify that a user can update their profile.
2. Write a test for a custom helper function you've added to your project.
3. Write a test for a middleware that only allows logged-in users to access certain routes.

Remember, the key to TDD is to write your tests first, then write the code to make those tests pass. Happy testing!