func: Introduce a server_expected_state kwarg to InstanceHelperMixin._live_migrate

Useful when testing live migration failures that leave the server in an
non ACTIVE state. This change also renames the migration_final_status
arg to migration_expected_state within the method to keep it in line
with _create_server.

Change-Id: Ie0852a89fc9423a92baa7c29a8806c0628cae220

Author: lyarwood

nova/tests/functional/compute/test_live_migration.py

@@ -162,16 +162,12 @@ def _fake_live_migration_with_rollback(
 
         # Migrate the instance and wait until the migration errors out thanks
         # to our mocked version of live_migration raising TestingException
-        self.api.post_server_action(
-            server['id'],
-            {'os-migrateLive': {'host': None, 'block_migration': 'auto'}})
-        self._wait_for_migration_status(server, ['error'])
+        self._live_migrate(server, 'error', server_expected_state='ERROR')
 
         # Assert that we called the fake live_migration method
         mock_lm.assert_called_once()
 
-        # Assert that the instance is listed as ERROR on the source
-        self._wait_for_state_change(server, 'ERROR')
+        # Assert that the instance is on the source
         server = self.api.get_server(server['id'])
         self.assertEqual(src_host, server['OS-EXT-SRV-ATTR:host'])
 

nova/tests/functional/integrated_helpers.py

@@ -430,13 +430,14 @@ def _resize_server(self, server, new_flavor):
         }
         self._migrate_or_resize(server, resize_req)
 
-    def _live_migrate(self, server, migration_final_status):
+    def _live_migrate(self, server, migration_expected_state,
+                      server_expected_state='ACTIVE'):
         self.api.post_server_action(
             server['id'],
             {'os-migrateLive': {'host': None,
                                 'block_migration': 'auto'}})
-        self._wait_for_state_change(server, 'ACTIVE')
-        self._wait_for_migration_status(server, [migration_final_status])
+        self._wait_for_state_change(server, server_expected_state)
+        self._wait_for_migration_status(server, [migration_expected_state])
 
 
 class PlacementHelperMixin: