Introduction to Unit Testing with PHPUnit

What is Unit Testing?

Unit testing is a software testing technique where individual units or methods of a program are tested independently to ensure they work properly. A unit test verifies that a specific code section behaves as expected, helping developers catch bugs early and improve code quality.

Benefits of Unit Testing

• Early Bug Detection: Identifies issues in code before deployment.
• Refactoring Confidence: Ensures modifications don’t break existing functionality.
• Improved Code Quality: Encourages writing modular and maintainable code.
• Faster Debugging: Helps isolate issues quickly.
• Automated Testing: Reduces manual testing effort.

Installing PHPUnit on Different Operating Systems

PHPUnit is a popular testing framework for PHP, allowing developers to write and run unit tests efficiently. Follow the steps below to install PHPUnit on Windows, Linux, and macOS.

Installing PHPUnit on Windows

Using Composer (Recommended)

1. Install Composer.
2. Open the command prompt and run:

composer require --dev phpunit/phpunit

1. Verify the installation:

vendor\bin\phpunit --version

Alternative: Manual Installation

1. Download the latest phpunit.phar from the official site.
2. Move it to a directory (e.g., C:\phpunit).
3. Add C:\phpunit to your system’s PATH.
4. Run:

php phpunit.phar --version

Installing PHPUnit on Linux and macOS

Using Composer (Recommended)

1. Install Composer:

curl -sS https://getcomposer.org/installer | php
mv composer.phar /usr/local/bin/composer

1. Install PHPUnit:

composer require --dev phpunit/phpunit

1. Verify the installation:

vendor/bin/phpunit --version

Alternative: Manual Installation

1. Download PHPUnit:

wget -O phpunit https://phar.phpunit.de/phpunit.phar
chmod +x phpunit
sudo mv phpunit /usr/local/bin/phpunit

1. Verify the installation:

phpunit --version

Setting Up a Basic PHPUnit Project

Step 1: Create a New PHP Project

Create a new directory for your project:

mkdir phpunit-demo && cd phpunit-demo

Initialize a new composer project:

composer init --no-interaction

Install PHPUnit:

composer require --dev phpunit/phpunit

Step 2: Write Your First Test

Create a tests directory and add a test file:

mkdir tests
nano tests/ExampleTest.php

Add the following code inside tests/ExampleTest.php:

<?php
use PHPUnit\Framework\TestCase;

class ExampleTest extends TestCase
{
    public function testAddition()
    {
        $this->assertEquals(4, 2 + 2);
    }
}

Step 3: Run PHPUnit Tests

Execute the test using:

./vendor/bin/phpunit tests

Expected output:

OK (1 test, 1 assertion)

Conclusion

This article introduced unit testing, installed PHPUnit on various operating systems, and set up a basic project with a simple test case. In the next part of this series, we will explore more advanced PHPUnit features, including test assertions, test doubles, and best practices.