Violating LSP principle

index.php

<?php
require_once 'Rectangle.php';
require_once 'Square.php';
require_once 'TestRectangleArea.php';

$r = new Rectangle();
$s = new Square();

// This will work.
// Rectangle behaves as expected
$t = new TestRectangleArea();
$t->testRectangleCalcArea($r);

// This will not work and will throw an exception
// In Math, Square is a Rectangle, but the object Square does not behave as Rectangle
$t->testRectangleCalcArea($s);

Rectangle.php

<?php
class Rectangle
{
    private $height;
    private $width;

    public function getHeight()
    {
        return (int) $this->height;
    }

    public function getWidth()
    {
        return (int) $this->width;
    }

    public function setHeight($height)
    {
        $this->height = (int) $height;
    }

    public function setWidth($width)
    {
        $this->width = (int) $width;
    }
}

RectangleArea.php

<?php
require_once 'Rectangle.php';

class RectangleArea
{
    public function calcArea(Rectangle $rectangle)
    {
        return $rectangle->getWidth() * $rectangle->getHeight();
    }
}

Square.php

<?php
require_once 'Rectangle.php';

class Square extends Rectangle
{
    public function setWidth($width)
    {
        parent::setWidth($width);
        parent::setHeight($width);
    }

    public function setHeight($height)
    {
        parent::setHeight($height);
        parent::setWidth($height);
    }
}

TestRectangleArea.php

<?php
require_once 'Rectangle.php';
require_once 'RectangleArea.php';

class TestRectangleArea
{
    public function testRectangleCalcArea(Rectangle $rectangle)
    {
        $w = 10;
        $h = 5;

        $rectangle->setWidth($w);
        $rectangle->setHeight($h);

        $recArea = new RectangleArea();

        if ($recArea->calcArea($rectangle) !== ($w * $h)) {
            throw new Exception('Você violou Liskov');
        }
    }
}