MAGETWO-39117: Updating qty that exceeds the qty in stock for registered customer by API should return error

removed unused code
added unit test

Author: Serhiy Shkolyarenko

lib/internal/Magento/Framework/Exception/CouldNotSaveMultiMessageException.php

@@ -6,7 +6,6 @@
 namespace Magento\Framework\Message;
 
 use Magento\Framework\Phrase;
-use Magento\Framework\Message\MessageInterface;
 
 /**
  * Factory to combine several messages into one

lib/internal/Magento/Framework/Message/PhraseFactory.php

@@ -0,0 +1,56 @@
+<?php
+/**
+ * Copyright © 2016 Magento. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Framework\Test\Unit\Message;
+
+use Magento\Framework\Message\PhraseFactory;
+use Magento\Framework\Message\Error;
+
+class PhraseFactoryTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @var PhraseFactory
+     */
+    private $factory;
+
+    protected function setUp()
+    {
+        $this->factory = new PhraseFactory();
+    }
+
+    /**
+     * @dataProvider dataProvider
+     * @param string $mainMessage
+     * @param array $subMessages
+     * @param string $separator
+     * @param string $expectedResult
+     */
+    public function testCreate($mainMessage, $subMessages, $separator, $expectedResult)
+    {
+        $result = (string)$this->factory->create($mainMessage, $subMessages, $separator);
+        $this->assertEquals($expectedResult, $result);
+    }
+
+    public function dataProvider()
+    {
+        $subMessage1 = new Error('go jogging');
+        $subMessage2 = new Error('paint the wall');
+        return [
+            'positive case' => [
+                'We will %1',
+                [$subMessage1, $subMessage2],
+                ' and ',
+                'We will go jogging and paint the wall',
+            ],
+            'broken messages' => [
+                'We will %1',
+                [$subMessage1, 'paint the wall'],
+                ' and ',
+                'We will go jogging and Cannot render error message!',
+            ],
+        ];
+    }
+
+}