Code refactor for ConfFixture

cfg.CONF is a global object, so we need not pass it to init
a ConfFixture.

We should import opts before use them in case that the opts
have not been registered.

Change-Id: I1a97df4d522325d9423b1c89cc9958de26704faa
Closes-Bug: #1492084

magnum/tests/base.py

@@ -83,7 +83,7 @@ class TestCase(base.BaseTestCase):
         self.mock_make_context = p.start()
         self.addCleanup(p.stop)
 
-        self.useFixture(conf_fixture.ConfFixture(cfg.CONF))
+        self.useFixture(conf_fixture.ConfFixture())
 
         self._base_test_obj_backup = copy.copy(
             objects_base.MagnumObjectRegistry._registry._obj_classes)

magnum/tests/conf_fixture.py

@@ -20,19 +20,19 @@ from oslo_log import log
 
 from magnum.common import config
 
-cfg.CONF.import_opt('host', 'magnum.common.service')
-log.register_options(cfg.CONF)
+CONF = cfg.CONF
+CONF.import_opt('host', 'magnum.common.service')
+CONF.import_opt('connection', 'oslo_db.options', group='database')
+CONF.import_opt('sqlite_synchronous', 'oslo_db.options', group='database')
 
 
 class ConfFixture(fixtures.Fixture):
     """Fixture to manage global conf settings."""
 
-    def __init__(self, conf):
-        self.conf = conf
-
     def _setUp(self):
-        self.conf.set_default('host', 'fake-mini')
-        self.conf.set_default('connection', "sqlite://", group='database')
-        self.conf.set_default('sqlite_synchronous', False, group='database')
+        log.register_options(cfg.CONF)
+        CONF.set_default('host', 'fake-mini')
+        CONF.set_default('connection', "sqlite://", group='database')
+        CONF.set_default('sqlite_synchronous', False, group='database')
         config.parse_args([], default_config_files=[])
-        self.addCleanup(self.conf.reset)
+        self.addCleanup(CONF.reset)