MAGETWO-59573: Braintree JS error on checkout after applying 100% discount coupon with free shipping enabled

-- functional test

Author: Stanislav Idolov

dev/tests/functional/tests/app/Magento/Checkout/Test/Constraint/AssertGrandTotalOrderReview.php

@@ -14,6 +14,13 @@
  */
 class AssertGrandTotalOrderReview extends AbstractConstraint
 {
+    /**
+     * Wait element.
+     *
+     * @var string
+     */
+    protected $waitElement = '.loading-mask';
+
     /**
      * Assert that Order Grand Total is correct on checkoutOnePage
      *
@@ -23,6 +30,7 @@ class AssertGrandTotalOrderReview extends AbstractConstraint
      */
     public function processAssert(CheckoutOnepage $checkoutOnepage, $grandTotal)
     {
+        $checkoutOnepage->getReviewBlock()->waitForElementNotVisible($this->waitElement);
         $checkoutReviewGrandTotal = $checkoutOnepage->getReviewBlock()->getGrandTotal();
 
         \PHPUnit_Framework_Assert::assertEquals(