Remove six from unit tests (part 3)

This is part of the steps to remove usage of six library, which is no
longer needed since python 2 support was removed.

Change-Id: I683a86eeab858c3f57c587e653ae53aff052fe9c

magnum/tests/unit/conductor/handlers/test_cluster_conductor.py

@@ -17,8 +17,6 @@
 from unittest import mock
 from unittest.mock import patch
 
-import six
-
 from heatclient import exc
 from oslo_service import loopingcall
 from pycadf import cadftaxonomy as taxonomy
@@ -380,9 +378,9 @@ class TestHandler(db_base.DbTestCase):
                                               mock_cert_manager,
                                               mock_trust_manager,
                                               mock_cluster_create):
-        error_message = six.u("""Invalid stack name 测试集群-zoyh253geukk
-                              must contain only alphanumeric or "_-."
-                              characters, must start with alpha""")
+        error_message = ("Invalid stack name 测试集群-zoyh253geukk must "
+                         "contain only alphanumeric or \"_-.\" characters, "
+                         "must start with alpha")
         mock_dr = mock.MagicMock()
         mock_driver.return_value = mock_dr
         mock_dr.create_cluster.side_effect = exc.HTTPBadRequest(error_message)

magnum/tests/unit/conf/test_conf.py

@@ -16,7 +16,6 @@ import collections
 from unittest import mock
 
 from oslo_config import cfg
-import six
 
 from magnum.conf import opts
 from magnum.tests import base
@@ -26,7 +25,7 @@ class ConfTestCase(base.TestCase):
 
     def test_list_opts(self):
         for group, opt_list in opts.list_opts():
-            if isinstance(group, six.string_types):
+            if isinstance(group, str):
                 self.assertEqual(group, 'DEFAULT')
             else:
                 self.assertIsInstance(group, cfg.OptGroup)