MAGETWO-84272: Update AbstractBackend.php magento#12120

 - fixed failed tests

Author: Oleksii Korshenko

app/code/Magento/Eav/Model/Entity/Attribute/Backend/AbstractBackend.php

@@ -231,13 +231,13 @@ public function validate($object)
         $attribute = $this->getAttribute();
         $attrCode = $attribute->getAttributeCode();
         $value = $object->getData($attrCode);
-        $label = $attribute->getFrontend()->getLabel();
 
         if ($attribute->getIsVisible()
             && $attribute->getIsRequired()
             && $attribute->isValueEmpty($value)
             && $attribute->isValueEmpty($attribute->getDefaultValue())
         ) {
+            $label = $attribute->getFrontend()->getLabel();
             throw new LocalizedException(__('The value of attribute "%1" must be set', $label));
         }
 
@@ -249,7 +249,8 @@ public function validate($object)
         }
 
         if ($attribute->getIsUnique()) {
-            if (!$attribute->getEntity()->checkAttributeUniqueValue($attribute, $object)) {               
+            if (!$attribute->getEntity()->checkAttributeUniqueValue($attribute, $object)) {
+                $label = $attribute->getFrontend()->getLabel();
                 throw new LocalizedException(__('The value of attribute "%1" must be unique', $label));
             }
         }

dev/tests/api-functional/testsuite/Magento/Customer/Api/AccountManagementTest.php

@@ -579,8 +579,8 @@ public function testValidateCustomerData()
         $validationResponse = $this->_webApiCall($serviceInfo, $requestData);
         $this->assertFalse($validationResponse['valid']);
 
-        $this->assertEquals('The value of attribute "firstname" must be set', $validationResponse['messages'][0]);
-        $this->assertEquals('The value of attribute "lastname" must be set', $validationResponse['messages'][1]);
+        $this->assertEquals('The value of attribute "First Name" must be set', $validationResponse['messages'][0]);
+        $this->assertEquals('The value of attribute "Last Name" must be set', $validationResponse['messages'][1]);
     }
 
     public function testIsReadonly()

dev/tests/integration/testsuite/Magento/Catalog/Controller/Adminhtml/CategoryTest.php

@@ -339,7 +339,7 @@ public function testSaveActionCategoryWithDangerRequest()
         );
         $this->dispatch('backend/catalog/category/save');
         $this->assertSessionMessages(
-            $this->equalTo(['The value of attribute "name" must be set']),
+            $this->equalTo(['The value of attribute "Name" must be set']),
             \Magento\Framework\Message\MessageInterface::TYPE_ERROR
         );
     }