PHPUnit

PHPUnit is a widely used testing framework in PHP. Automated testing allows developers to ensure their code functions as expected. With PHPUnit, you can write test cases in PHP to check the functionality of your codebase. It's particularly good for executing unit tests - tests that verify individual parts of the software. PHPUnit supports several types of assertions, making it versatile for any testing requirement. Here's a simple PHPUnit test case:

<?php
use PHPUnit\Framework\TestCase;

class StackTest extends TestCase
{
    public function testPushAndPop()
    {
        $stack = [];
        $this->assertEquals(0, count($stack));

        array_push($stack, 'foo');
        $this->assertEquals('foo', $stack[count($stack)-1]);
        $this->assertEquals(1, count($stack));

        $this->assertEquals('foo', array_pop($stack));
        $this->assertEquals(0, count($stack));
    }
}
?>

In this example, we’re testing the 'push' and 'pop' functionality of an array.