MAGETWO-54303: Issue with fetching shipping charges based on city

 added unit tests

Author: Serhiy Shkolyarenko

app/code/Magento/Fedex/Test/Unit/Model/CarrierTest.php

@@ -148,6 +148,30 @@ protected function setUp()
         );
     }
 
+    public function testSetRequestWithoutCity()
+    {
+        $requestMock = $this->getMockBuilder(\Magento\Quote\Model\Quote\Address\RateRequest::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['getDestCity'])
+            ->getMock();
+        $requestMock->expects($this->once())
+            ->method('getDestCity')
+            ->willReturn(null);
+        $this->_model->setRequest($requestMock);
+    }
+
+    public function testSetRequestWithCity()
+    {
+        $requestMock = $this->getMockBuilder(\Magento\Quote\Model\Quote\Address\RateRequest::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['getDestCity'])
+            ->getMock();
+        $requestMock->expects($this->exactly(2))
+            ->method('getDestCity')
+            ->willReturn('Small Town');
+        $this->_model->setRequest($requestMock);
+    }
+
     /**
      * Callback function, emulates getValue function
      * @param $path