PHPUnit Basics (Write Your First Unit Test)

Testing protects your code from regressions.

Step 1: Install PHPUnit (Composer)

composer require --dev phpunit/phpunit

Step 2: Create a simple function

File: src/Math.php

<?php
function add(int $a, int $b): int {
  return $a + $b;
}

Step 3: Write a test

File: tests/MathTest.php

<?php
use PHPUnit\Framework\TestCase;

require_once __DIR__ . "/../src/Math.php";

class MathTest extends TestCase {
  public function testAdd() {
    $this->assertEquals(5, add(2, 3));
  }
}

Step 4: Run tests

./vendor/bin/phpunit

Next: Mocking dependencies, test services without real database calls.