MAGETWO-35155: Error appears on Shipping Method page during MultiAdress Checkout if countries are not allowed for shipping

 - unit test fix
(cherry picked from commit 12c93a5)

Author: Ievgen Shakhsuvarov

app/code/Magento/GiftMessage/Test/Unit/Model/Type/Plugin/MultishippingTest.php

@@ -41,7 +41,11 @@ protected function setUp()
         );
     }
 
-    public function testBeforeSetShippingMethods()
+    /**
+     * @dataProvider beforeSetShippingMethodsDataProvider
+     * @param array|null $methods
+     */
+    public function testBeforeSetShippingMethods($methods)
     {
         $this->requestMock->expects($this->once())
             ->method('getParam')
@@ -52,6 +56,17 @@ public function testBeforeSetShippingMethods()
         $subjectMock->expects($this->once())->method('getQuote')->will($this->returnValue($quoteMock));
         $this->messageMock->expects($this->once())->method('add')->with('Expected Value', $quoteMock);
 
-        $this->plugin->beforeSetShippingMethods($subjectMock, []);
+        $this->plugin->beforeSetShippingMethods($subjectMock, $methods);
+    }
+
+    /**
+     * @return array
+     */
+    public function beforeSetShippingMethodsDataProvider()
+    {
+        return [
+            [null],
+            [[]]
+        ];
     }
 }