MAGETWO-55908: Prepare PR

dev/tests/integration/testsuite/Magento/Customer/Model/Config/Source/Group/MultiselectTest.php

+<?php
+/**
+ * Copyright © 2016 Magento. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Customer\Model\Config\Source\Group;
+
+use Magento\TestFramework\Helper\Bootstrap;
+
+/**
+ * Class \Magento\Customer\Model\Config\Source\Group\Multiselect
+ */
+class MultiselectTest extends \PHPUnit_Framework_TestCase
+{
+    public function testToOptionArray()
+    {
+        /** @var Multiselect $multiselect */
+        $multiselect = Bootstrap::getObjectManager()->get(
+            \Magento\Customer\Model\Config\Source\Group\Multiselect::class
+        );
+
+        $options = $multiselect->toOptionArray();
+        $optionsToCompare = [];
+        foreach ($options as $option) {
+            if (is_array($option['value'])) {
+                $optionsToCompare = array_merge($optionsToCompare, $option['value']);
+            } else {
+                $optionsToCompare[] = $option;
+            }
+        }
+        sort($optionsToCompare);
+        $this->assertEquals(
+            [
+                ['value' => 1, 'label' => 'General'],
+                ['value' => 2, 'label' => 'Wholesale'],
+                ['value' => 3, 'label' => 'Retailer'],
+            ],
+            $optionsToCompare
+        );
+    }
+}