AC-12860: Weight unit issue fixed

Author: hemanthjadobe

app/code/Magento/Catalog/Block/Adminhtml/Product/Helper/Form/Weight.php

@@ -122,7 +122,7 @@ public function getElementHtml()
         $html .= '<label class="admin__addon-suffix" for="' .
             $this->getHtmlId() .
             '"><span>' .
-            $this->directoryHelper->getWeightUnit() .
+            $this->_escaper->escapeHtml($this->directoryHelper->getWeightUnit()) .
             '</span></label></div>';
 
         if ($afterElementJs = $this->getAfterElementJs()) {

app/code/Magento/Directory/Model/Config/Backend/WeightUnit.php

@@ -0,0 +1,81 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Directory\Model\Config\Backend;
+
+use LocalizedException;
+use Magento\Directory\Model\Config\Source\WeightUnit as Source;
+use Magento\Framework\App\Cache\TypeListInterface;
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\App\Config\Value;
+use Magento\Framework\Data\Collection\AbstractDb;
+use Magento\Framework\Model\Context;
+use Magento\Framework\Model\ResourceModel\AbstractResource;
+use Magento\Framework\Registry;
+
+/**
+ * Backend source for weight unit configuration field
+ */
+class WeightUnit extends Value
+{
+    /**
+     * @var Source
+     */
+    private $source;
+
+    /**
+     * @param Source $source
+     * @param Context $contesxt
+     * @param Registry $registry
+     * @param ScopeConfigInterface $config
+     * @param TypeListInterface $cacheTypeList
+     * @param CookieLifetimeValidator $configValidator
+     * @param AbstractResource $resource
+     * @param AbstractDb $resourceCollection
+     * @param array $data
+     *
+     * @codeCoverageIgnore
+     */
+    public function __construct(
+        Source $source,
+        Context $context,
+        Registry $registry,
+        ScopeConfigInterface $config,
+        TypeListInterface $cacheTypeList,
+        AbstractResource $resource = null,
+        AbstractDb $resourceCollection = null,
+        array $data = []
+    ) {
+        $this->source = $source;
+        parent::__construct($context, $registry, $config, $cacheTypeList, $resource, $resourceCollection, $data);
+    }
+
+    /**
+     * Check whether weight unit value is acceptable or not
+     *
+     * @return $this
+     */
+    public function beforeSave()
+    {
+        if ($this->isValueChanged()) {
+            $weightUnit = $this->getData('value');
+            if (!in_array($weightUnit, $this->getOptions())) {
+                throw new LocalizedException(__('There was an error save new configuration value.'));
+            }
+        }
+        return parent::beforeSave();
+    }
+
+    /**
+     * Get available options for weight unit
+     * 
+     * @return array
+     */
+    private function getOptions()
+    {
+        $options = $this->source->toOptionArray();
+        return array_column($options, 'value');
+    }
+}

app/code/Magento/Directory/etc/adminhtml/system.xml

@@ -157,6 +157,7 @@
                 <field id="weight_unit" translate="label" type="select" sortOrder="7" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Weight Unit</label>
                     <source_model>Magento\Directory\Model\Config\Source\WeightUnit</source_model>
+                    <backend_model>Magento\Directory\Model\Config\Backend\WeightUnit</backend_model>
                 </field>
             </group>
         </section>