<?php
declare(strict_types=1);

class StackTest extends \PHPUnit\Framework\TestCase
{
    public function testPushAndPop(): void
    {
        $stack = [];
        $this->assertSame(0, count($stack));
    
        $stack[] = 'foo';
        $this->assertSame('foo', $stack[count($stack)-1]);
        $this->assertSame(1, count($stack));
        
        $this->assertSame('foo', array_pop($stack));
        $this->assertSame(0, count($stack));
    }
}