ACP2E-2428: Coupon code whitespace issue in checkout page

- trimming coupon codes before adding to quote

Author: aplapana

app/code/Magento/Quote/Model/GuestCart/GuestCouponManagement.php

@@ -57,7 +57,7 @@ public function set($cartId, $couponCode)
     {
         /** @var $quoteIdMask QuoteIdMask */
         $quoteIdMask = $this->quoteIdMaskFactory->create()->load($cartId, 'masked_id');
-        return $this->couponManagement->set($quoteIdMask->getQuoteId(), $couponCode);
+        return $this->couponManagement->set($quoteIdMask->getQuoteId(), trim($couponCode));
     }
 
     /**

app/code/Magento/Quote/Test/Unit/Model/GuestCart/GuestCouponManagementTest.php

@@ -56,7 +56,7 @@ protected function setUp(): void
         $objectManager = new ObjectManager($this);
         $this->couponManagementMock = $this->getMockForAbstractClass(CouponManagementInterface::class);
 
-        $this->couponCode = 'test_coupon_code';
+        $this->couponCode = ' test_coupon_code';
         $this->maskedCartId = 'f216207248d65c789b17be8545e0aa73';
         $this->cartId = 123;
 
@@ -83,7 +83,10 @@ public function testGet()
 
     public function testSet()
     {
-        $this->couponManagementMock->expects($this->once())->method('set')->willReturn(true);
+        $this->couponManagementMock->expects($this->once())
+            ->method('set')
+            ->with($this->cartId, trim($this->couponCode))
+            ->willReturn(true);
         $this->assertTrue($this->model->set($this->maskedCartId, $this->couponCode));
     }
 

app/code/Magento/SalesRule/view/frontend/web/js/view/payment/discount.js

@@ -60,7 +60,9 @@ define([
          */
         validate: function () {
             var form = '#discount-form';
-
+            $(form + " input[type='text']").each(function () {
+                $(this).val($(this).val().trim());
+            })
             return $(form).validation() && $(form).validation('isValid');
         }
     });