Add revert resized server functional negative tests

The negative tests of revert resized server API are not covered enough
in functional tests. We want to add the conflict tests
of when this API runs in the unexpected state of server.
* Case of revert resized server API, the server status must be VERIFY_RESIZE.

Change-Id: I67d7173156fb8cc93b209d6563b7d31c400cc2b3

nova/tests/functional/test_servers.py

@@ -590,6 +590,29 @@ class ServersTest(ServersTestBase):
         # Cleanup
         self._delete_server(created_server_id)
 
+    def test_revert_resized_server_negative_invalid_state(self):
+        # Create server
+        server = self._build_minimal_create_server_request()
+        created_server = self.api.post_server({"server": server})
+        created_server_id = created_server['id']
+        found_server = self._wait_for_state_change(created_server, 'BUILD')
+        self.assertEqual('ACTIVE', found_server['status'])
+
+        # Revert resized server in ACTIVE
+        # NOTE(yatsumi): When revert resized server API runs,
+        # the server status must be VERIFY_RESIZE.
+        # By returning 409, I want to confirm that the ACTIVE server does not
+        # cause unexpected behavior.
+        post = {'revertResize': {}}
+        ex = self.assertRaises(client.OpenStackApiException,
+                               self.api.post_server_action,
+                               created_server_id, post)
+        self.assertEqual(409, ex.response.status_code)
+        self.assertEqual('ACTIVE', found_server['status'])
+
+        # Cleanup
+        self._delete_server(created_server_id)
+
 
 class ServersTestV21(ServersTest):
     api_major_version = 'v2.1'