PHPSpec test and classes

Cart.php

<?php namespace Crinsane\ShoppingCart;

use Countable;
use Illuminate\Contracts\Events\Dispatcher;
use Symfony\Component\HttpFoundation\Session\SessionInterface;

class Cart implements Countable {

	/**
	 * Implementation of the Symfony SessionInterface
	 *
	 * @var \Symfony\Component\HttpFoundation\Session\SessionInterface
	 */
	protected $session;

	/**
	 * Implementation of the Illuminate Dispatcher contract
	 *
	 * @var \Illuminate\Contracts\Events\Dispatcher
	 */
	protected $events;

	/**
	 * The collection of items in the cart
	 *
	 * @var \Crinsane\ShoppingCart\CartItemCollection
	 */
	protected $items;

	/**
	 * Cart constructor
	 *
	 * @param \Symfony\Component\HttpFoundation\Session\SessionInterface $session
	 * @param \Illuminate\Contracts\Events\Dispatcher                    $events
	 */
	public function __construct(SessionInterface $session, Dispatcher $events)
    {
	    $this->session = $session;
	    $this->events = $events;

	    $this->items = new CartItemCollection();
    }


	/**
	 * Add one or more cart items to the cart
	 *
	 * @param \Crinsane\ShoppingCart\CartItem $item
	 * @param int                             $qty
	 */
	public function add(CartItem $item, $qty = 1)
    {
	    $rowId = $this->generateRowId($item);

	    $this->items->put($rowId, [
			'id'    => $item->getId(),
			'name'  => $item->getName(),
			'qty'   => $qty,
			'price' => $item->getPrice(),
			'item'  => $item
		]);
    }

	/**
	 * Generate a unique rowId
	 *
	 * @param \Crinsane\ShoppingCart\CartItem $item
	 * @return string
	 */
	protected function generateRowId(CartItem $item)
	{
		return md5($item->getId() . serialize($item->getOptions()));
	}

	/**
	 * (PHP 5 &gt;= 5.1.0)<br/>
	 * Count elements of an object
	 *
	 * @link http://php.net/manual/en/countable.count.php
	 * @return int The custom count as an integer.
	 * </p>
	 * <p>
	 * The return value is cast to an integer.
	 */
	public function count()
	{
		return $this->items->sum('qty');
	}


	/**
	 * Count the number of rows in the collection
	 *
	 * @return int
	 */
	public function rows()
    {
        return $this->items->count();
    }

}

CartItem.php

<?php namespace Crinsane\ShoppingCart;

interface CartItem {

	/**
	 * Get the unique ID of the item
	 *
	 * @return int|string
	 */
	public function getId();

	/**
	 * Get the name of the item
	 *
	 * @return string
	 */
	public function getName();

	/**
	 * Get the price of the item
	 *
	 * @return float
	 */
	public function getPrice();

	/**
	 * Get an array of options
	 *
	 * @return array
	 */
	public function getOptions();

}

CartSpec.php

<?php namespace spec\Crinsane\ShoppingCart;

use Crinsane\ShoppingCart\CartItem;
use Illuminate\Contracts\Events\Dispatcher;
use PhpSpec\ObjectBehavior;
use Prophecy\Argument;
use Symfony\Component\HttpFoundation\Session\SessionInterface;

class CartSpec extends ObjectBehavior {

	public function let(SessionInterface $session, Dispatcher $events)
	{
		$session->beADoubleOf('Symfony\Component\HttpFoundation\Session\SessionInterface');
		$events->beADoubleOf('Illuminate\Contracts\Events\Dispatcher');
		$this->beConstructedWith($session, $events);
	}

    public function it_is_initializable()
    {
        $this->shouldHaveType('Crinsane\ShoppingCart\Cart');
    }

	public function it_stores_a_collection_of_cart_items(CartItem $cartItem)
	{
		$this->add($cartItem, 1);

		$this->shouldHaveCount(1);
	}

	public function it_can_add_multiple_instances_of_a_cart_item(CartItem $cartItem1, CartItem $cartItem2)
	{
		$cartItem1->getId()->willReturn(1);
		$cartItem1->getName()->willReturn(null);
		$cartItem1->getPrice()->willReturn(null);
		$cartItem1->getOptions()->willReturn([]);

		$cartItem2->getId()->willReturn(2);
		$cartItem2->getName()->willReturn(null);
		$cartItem2->getPrice()->willReturn(null);
		$cartItem2->getOptions()->willReturn([]);

		$this->add($cartItem1);
		$this->add($cartItem2);

		$this->shouldHaveCount(2);
	}

}