Merge branch 'MAGETWO-64399-PR-8474' into develop-prs

Author: Oleksii Korshenko

app/code/Magento/Quote/Model/Quote/Validator/MinimumOrderAmount/ValidationMessage.php

@@ -38,7 +38,9 @@ public function __construct(
     }
 
     /**
-     * @return \Magento\Framework\Phrase|mixed
+     * Get validation message.
+     *
+     * @return \Magento\Framework\Phrase
      * @throws \Zend_Currency_Exception
      */
     public function getMessage()
@@ -56,6 +58,9 @@ public function getMessage()
                 )
             );
             $message = __('Minimum order amount is %1', $minimumAmount);
+        } else {
+            //Added in order to address the issue: https://github.com/magento/magento2/issues/8287
+            $message = __($message);
         }
 
         return $message;

app/code/Magento/Quote/Test/Unit/Model/Quote/Validator/MinimumOrderAmount/ValidationMessageTest.php

@@ -5,6 +5,8 @@
  */
 namespace Magento\Quote\Test\Unit\Model\Quote\Validator\MinimumOrderAmount;
 
+use Magento\Framework\Phrase;
+
 class ValidationMessageTest extends \PHPUnit_Framework_TestCase
 {
     /**
@@ -86,6 +88,9 @@ public function testGetConfigMessage()
             ->with('sales/minimum_order/description', \Magento\Store\Model\ScopeInterface::SCOPE_STORE)
             ->willReturn($configMessage);
 
-        $this->assertEquals($configMessage, $this->model->getMessage());
+        $message = $this->model->getMessage();
+
+        $this->assertEquals(Phrase::class , get_class($message));
+        $this->assertEquals($configMessage, $message->__toString());
     }
 }