MAGETWO-90569: Empty product attributes of dropdown/swatch types display as "No" of the storefront

Author: StasKozar

app/code/Magento/Eav/Model/Entity/Attribute/Frontend/AbstractFrontend.php

@@ -165,7 +165,7 @@ public function getValue(\Magento\Framework\DataObject $object)
                 $options = $opt->getAllOptions();
                 if ($options) {
                     foreach ($options as $option) {
-                        if ($option['value'] == $value) {
+                        if ($option['value'] === $value) {
                             $valueOption = $option['label'];
                         }
                     }

dev/tests/integration/testsuite/Magento/Catalog/_files/dropdown_attribute.php

@@ -32,8 +32,8 @@
             'is_filterable_in_search'       => 0,
             'is_used_for_promo_rules'       => 0,
             'is_html_allowed_on_front'      => 1,
-            'is_visible_on_front'           => 0,
-            'used_in_product_listing'       => 0,
+            'is_visible_on_front'           => 1,
+            'used_in_product_listing'       => 1,
             'used_for_sort_by'              => 0,
             'frontend_label'                => ['Drop-Down Attribute'],
             'backend_type'                  => 'varchar',

dev/tests/integration/testsuite/Magento/Eav/Model/Entity/Attribute/Frontend/DefaultFrontendTest.php

@@ -78,6 +78,21 @@ public function testGetSelectOptions()
         );
     }
 
+    /**
+     * @magentoDataFixture Magento/Catalog/_files/dropdown_attribute.php
+     * @return void
+     */
+    public function testAttributeEntityValueNotSet()
+    {
+        $entity = $this->objectManager->create(\Magento\Catalog\Model\Product::class);
+        $entity->setStoreId(0);
+        $entity->load(1);
+        $frontEnd = $this->attribute->loadByCode('catalog_product', 'dropdown_attribute');
+        $value = $frontEnd->getFrontend()->getValue($entity);
+
+        $this->assertFalse($value);
+    }
+
     /**
      * Cache key generation
      * @return string