Use ConfigFixture to ensure config settings are reverted

Update the test configuration management code to use a ConfigFixture so
that configuration changes are rolled back at the end of each test.

Also fix the initialization order in TestSwiftParams to ensure that the
base class is configured before local customizations are applied.

Change-Id: I27620e3d4caf95e2c75fbf2cf2716ae1337030c7

glance/tests/unit/common/test_swift_store_utils.py

@@ -22,11 +22,11 @@ from glance.tests.unit import base
 class TestSwiftParams(base.IsolatedUnitTest):
 
     def setUp(self):
+        super(TestSwiftParams, self).setUp()
         conf_file = "glance-swift.conf"
         test_dir = self.useFixture(fixtures.TempDir()).path
         self.swift_config_file = self._copy_data_file(conf_file, test_dir)
         self.config(swift_store_config_file=self.swift_config_file)
-        super(TestSwiftParams, self).setUp()
 
     def tearDown(self):
         super(TestSwiftParams, self).tearDown()

glance/tests/utils.py

@@ -25,6 +25,7 @@ import subprocess
 
 import fixtures
 from oslo_config import cfg
+from oslo_config import fixture as cfg_fixture
 from oslo_log import log
 from oslo_serialization import jsonutils
 from oslo_utils import timeutils
@@ -64,6 +65,8 @@ class BaseTestCase(testtools.TestCase):
     def setUp(self):
         super(BaseTestCase, self).setUp()
 
+        self._config_fixture = self.useFixture(cfg_fixture.Config())
+
         # NOTE(bcwaldon): parse_args has to be called to register certain
         # command-line options - specifically we need config_dir for
         # the following policy tests
@@ -122,9 +125,7 @@ class BaseTestCase(testtools.TestCase):
         All overrides are automatically cleared at the end of the current
         test by the fixtures cleanup process.
         """
-        group = kw.pop('group', None)
-        for k, v in six.iteritems(kw):
-            CONF.set_override(k, v, group)
+        self._config_fixture.config(**kw)
 
 
 class requires(object):