VMware: treat cases when SOAP reply does not have a body

There are cases when the SOAP reply does not return a body (for
example UnregisterVM may return this when running the CI).

This patch ensures that an exception is not thrown.

Change-Id: I394320641c648effd1209345cfd729e975f12aab
Closes-bug: #1300788

oslo/vmware/vim.py

@@ -165,6 +165,8 @@ class Vim(object):
                     # of the managed object.
                     managed_object = vim_util.get_moref(managed_object,
                                                         managed_object)
+                if managed_object is None:
+                    return
                 request = getattr(self.client.service, attr_name)
                 LOG.debug(_("Invoking %(attr_name)s on %(moref)s."),
                           {'attr_name': attr_name,

tests/test_vim.py

@@ -25,6 +25,7 @@ import suds
 
 from oslo.vmware import exceptions
 from oslo.vmware import vim
+from oslo.vmware import vim_util
 from tests import base
 
 
@@ -231,6 +232,13 @@ class VimTest(base.TestCase):
         self.assertRaises(exceptions.VimConnectionException,
                           lambda: vim_obj.powerOn(managed_object))
 
+    @mock.patch.object(vim_util, 'get_moref', return_value=None)
+    def test_vim_request_handler_no_value(self, mock_moref):
+        managed_object = 'VirtualMachine'
+        vim_obj = vim.Vim()
+        ret = vim_obj.UnregisterVM(managed_object)
+        self.assertIsNone(ret)
+
     def _test_vim_request_handler_with_exception(self, message, exception):
         managed_object = 'VirtualMachine'