Updated test case to increase the coverage

Author: sijeesh

tests/unit/image_streamer/resources/test_os_volumes.py

@@ -90,7 +90,7 @@ def test_download_archive_called_once_with_uri(self, mock_download):
                                               '~/archive.log')
 
     @mock.patch.object(ResourceClient, 'get')
-    def test_get_storage(self, mock_download):
+    def test_get_storage(self, mock_get):
         uri = '/rest/os-volumes/3518be0e-17c1-4189-8f81-83f3724f6155/storage'
         self._client.get(uri)
-        mock_download.assert_called_once_with('/rest/os-volumes/3518be0e-17c1-4189-8f81-83f3724f6155/storage')
+        mock_get.assert_called_once_with('/rest/os-volumes/3518be0e-17c1-4189-8f81-83f3724f6155/storage')