Cleaned up the testsuite a bit

tests/Fixtures/BuyableProduct.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace Gloudemans\Tests\Shoppingcart\Fixtures;
+
+use Gloudemans\Shoppingcart\Contracts\Buyable;
+
+class BuyableProduct implements Buyable
+{
+    /**
+     * @var int|string
+     */
+    private $id;
+
+    /**
+     * @var string
+     */
+    private $name;
+
+    /**
+     * @var float
+     */
+    private $price;
+
+    /**
+     * BuyableProduct constructor.
+     *
+     * @param int|string $id
+     * @param string     $name
+     * @param float      $price
+     */
+    public function __construct($id = 1, $name = 'Item name', $price = 10.00)
+    {
+        $this->id = $id;
+        $this->name = $name;
+        $this->price = $price;
+    }
+
+    /**
+     * Get the identifier of the Buyable item.
+     *
+     * @return int|string
+     */
+    public function getBuyableIdentifier($options = null)
+    {
+        return $this->id;
+    }
+
+    /**
+     * Get the description or title of the Buyable item.
+     *
+     * @return string
+     */
+    public function getBuyableDescription($options = null)
+    {
+        return $this->name;
+    }
+
+    /**
+     * Get the price of the Buyable item.
+     *
+     * @return float
+     */
+    public function getBuyablePrice($options = null)
+    {
+        return $this->price;
+    }
+}