Inject user context instead of using global implementation

Author: rogyar

app/code/Magento/QuoteGraphQl/Model/Resolver/Cart/CreateEmptyCart.php

@@ -7,6 +7,7 @@
 
 namespace Magento\QuoteGraphQl\Model\Resolver\Cart;
 
+use Magento\Authorization\Model\UserContextInterface;
 use Magento\Framework\GraphQl\Config\Element\Field;
 use Magento\Framework\GraphQl\Query\Resolver\Value;
 use Magento\Framework\GraphQl\Query\Resolver\ValueFactory;
@@ -42,21 +43,29 @@ class CreateEmptyCart implements ResolverInterface
      */
     private $quoteIdMaskFactory;
 
+    /**
+     * @var UserContextInterface
+     */
+    private $userContext;
+
     /**
      * @param CartManagementInterface $cartManagement
      * @param GuestCartManagementInterface $guestCartManagement
      * @param ValueFactory $valueFactory
+     * @param UserContextInterface $userContext
      * @param QuoteIdMaskFactory $quoteIdMaskFactory
      */
     public function __construct(
         CartManagementInterface $cartManagement,
         GuestCartManagementInterface $guestCartManagement,
         ValueFactory $valueFactory,
+        UserContextInterface $userContext,
         QuoteIdMaskFactory $quoteIdMaskFactory
     ) {
         $this->cartManagement = $cartManagement;
         $this->guestCartManagement = $guestCartManagement;
         $this->valueFactory = $valueFactory;
+        $this->userContext = $userContext;
         $this->quoteIdMaskFactory = $quoteIdMaskFactory;
     }
 
@@ -65,7 +74,7 @@ public function __construct(
      */
     public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null) : Value
     {
-        $customerId = $context->getUserId();
+        $customerId = $this->userContext->getUserId();
 
         if ($customerId) {
             $cartId = $this->cartManagement->createEmptyCartForCustomer($customerId);

app/code/Magento/QuoteGraphQl/composer.json

@@ -5,6 +5,7 @@
     "require": {
         "php": "~7.1.3||~7.2.0",
         "magento/framework": "*",
+        "magento/module-authorization": "*",
         "magento/module-quote": "*"
     },
     "suggest": {