get cart/quote in Observer

Question

I have an observer checkout_cart_add_product_complete which gives me a product. But not the cart. I want to add data to the cart based on the product.

My observer definition.

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="checkout_cart_add_product_complete">
        <observer name="test_lease_controller_front_send_response_before" instance="Test\Lease\Observer\AddtoCart"/>
    </event>
</config>

The class:

<?php
namespace Test\Lease\Observer;

use \Magento\Framework\Event\Observer;
use \Magento\Framework\Event\ObserverInterface;

class AddtoCart implements ObserverInterface {
    public function execute(Observer $observer) {
        /** @var \Magento\Catalog\Model\Product\Interceptor $product */
        $product = $observer->getProduct();

        // need cart here
    }
}

I know the way to do this is dependency injection but I just can't figure it out.
I've red a few things but can't figure it out.

Can somebody help me get started?

Answer 1

I can't explain how it works. But Magento2 will autoload all classes passed specified in the __constructor. It will use reflection in some way.
I mostly copied \Magento\Wishlist\Observer\AddToCart, which observed the same event. The result:

<?php
namespace Marissen\Lease\Observer;

use \Magento\Framework\Event\Observer;
use \Magento\Framework\Event\ObserverInterface;

use \Magento\Checkout\Model\Session as CheckoutSession;

class AddtoCart implements ObserverInterface {

    /** @var CheckoutSession */
    protected $checkoutSession;

    /**
     * @param CheckoutSession $checkoutSession
     */
    public function __construct(CheckoutSession $checkoutSession) {
        $this->checkoutSession = $checkoutSession;
    }

    public function execute(Observer $observer) {
        /** @var \Magento\Catalog\Model\Product\Interceptor $product */
        $product = $observer->getProduct();

        /** @var \Magento\Quote\Model\Quote  */
        $quote = $this->checkoutSession->getQuote();
    }
}