MAGETWO-71229: Warning message is cached and shown a few times on the shopping cart

Author: VladimirZaets

app/code/Magento/Catalog/view/frontend/templates/product/view/addtocart.phtml

@@ -40,7 +40,8 @@
     </div>
 </div>
 <?php endif; ?>
-<script type="text/x-magento-init">
+<?php if ($block->isRedirectToCartEnabled()) : ?>
+    <script type="text/x-magento-init">
     {
         "#product_addtocart_form": {
             "Magento_Catalog/product/view/validation": {
@@ -49,13 +50,11 @@
         }
     }
 </script>
-<?php if (!$block->isRedirectToCartEnabled()) : ?>
-<script type="text/x-magento-init">
+<?php else : ?>
+    <script type="text/x-magento-init">
     {
         "#product_addtocart_form": {
-            "catalogAddToCart": {
-                "bindSubmit": false
-            }
+            "Magento_Catalog/js/validate-product": {}
         }
     }
 </script>

app/code/Magento/Catalog/view/frontend/web/js/validate-product.js

@@ -0,0 +1,48 @@
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+define([
+    'jquery',
+    'mage/mage',
+    'Magento_Catalog/product/view/validation',
+    'catalogAddToCart'
+], function ($) {
+    'use strict';
+
+    $.widget('mage.productValidate', {
+        options: {
+            bindSubmit: false,
+            radioCheckboxClosest: '.nested'
+        },
+
+        /**
+         * Uses Magento's validation widget for the form object.
+         * @private
+         */
+        _create: function () {
+            var bindSubmit = this.options.bindSubmit;
+
+            this.element.validation({
+                radioCheckboxClosest: this.options.radioCheckboxClosest,
+
+                /**
+                 * Uses catalogAddToCart widget as submit handler.
+                 * @param {Object} form
+                 * @returns {Boolean}
+                 */
+                submitHandler: function (form, event) {
+                    var jqForm = $(form).catalogAddToCart({
+                        bindSubmit: bindSubmit
+                    });
+
+                    jqForm.catalogAddToCart('submitForm', jqForm, event);
+
+                    return false;
+                }
+            });
+        }
+    });
+
+    return $.mage.productValidate;
+});

app/code/Magento/Theme/view/frontend/web/js/view/messages.js

@@ -21,7 +21,7 @@ define([
         initialize: function () {
             this._super();
 
-            this.cookieMessages = $.cookieStorage.get('mage-messages');
+            this.cookieMessages = _.unique($.cookieStorage.get('mage-messages'), 'text');
             this.messages = customerData.get('messages').extend({
                 disposableCustomerData: 'messages'
             });