Adds a backend test fixture

Moves the existing backend setup logic into a fixture. Future commits
will make it possible to just specify the backends needed for a
particular commit.

Change-Id: Ic4a9637a34d9523e6da46e3ea705676b34cf67a5

keystone/tests/unit/core.py

@@ -41,16 +41,13 @@ from sqlalchemy import exc
 import testtools
 from testtools import testcase
 
-from keystone import auth
 from keystone.common import dependency
-from keystone.common.kvs import core as kvs_core
 from keystone.common import request
 from keystone.common import sql
 import keystone.conf
 from keystone import exception
 from keystone.identity.backends.ldap import common as ks_ldap
 from keystone import notifications
-from keystone.server import common
 from keystone.tests.unit import ksfixtures
 from keystone.version import controllers
 from keystone.version import service
@@ -694,23 +691,7 @@ class TestCase(BaseTestCase):
 
     def load_backends(self):
         """Initialize each manager and assigns them to an attribute."""
-        # TODO(blk-u): Shouldn't need to clear the registry here, but some
-        # tests call load_backends multiple times. These should be fixed to
-        # only call load_backends once.
-        dependency.reset()
-
-        # TODO(morganfainberg): Shouldn't need to clear the registry here, but
-        # some tests call load_backends multiple times.  Since it is not
-        # possible to re-configure a backend, we need to clear the list.  This
-        # should eventually be removed once testing has been cleaned up.
-        kvs_core.KEY_VALUE_STORE_REGISTRY.clear()
-
-        self.clear_auth_plugin_registry()
-        drivers, _unused = common.setup_backends()
-
-        for manager_name, manager in drivers.items():
-            setattr(self, manager_name, manager)
-        self.addCleanup(self.cleanup_instance(*list(drivers.keys())))
+        self.useFixture(ksfixtures.BackendLoader(self))
 
     def load_fixtures(self, fixtures):
         """Hacky basic and naive fixture loading based on a python module.
@@ -817,10 +798,6 @@ class TestCase(BaseTestCase):
     def loadapp(self, config, name='main'):
         return service.loadapp(self._paste_config(config), name=name)
 
-    def clear_auth_plugin_registry(self):
-        auth.controllers.AUTH_METHODS.clear()
-        auth.controllers.AUTH_PLUGINS_LOADED = False
-
     def assertCloseEnoughForGovernmentWork(self, a, b, delta=3):
         """Assert that two datetimes are nearly equal within a small delta.
 

keystone/tests/unit/ksfixtures/__init__.py

@@ -12,6 +12,7 @@
 # limitations under the License.
 
 from keystone.tests.unit.ksfixtures.auth_plugins import ConfigAuthPlugins  # noqa
+from keystone.tests.unit.ksfixtures.backendloader import BackendLoader  # noqa
 from keystone.tests.unit.ksfixtures.cache import Cache  # noqa
 from keystone.tests.unit.ksfixtures.key_repository import KeyRepository  # noqa
 from keystone.tests.unit.ksfixtures.policy import Policy  # noqa

keystone/tests/unit/ksfixtures/backendloader.py

@@ -0,0 +1,55 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import fixtures
+
+from keystone import auth
+from keystone.common import dependency
+from keystone.common.kvs import core as kvs_core
+from keystone.server import common
+
+
+class BackendLoader(fixtures.Fixture):
+    """Initialize each manager and assigns them to an attribute."""
+
+    def __init__(self, testcase):
+        super(BackendLoader, self).__init__()
+        self._testcase = testcase
+
+    def setUp(self):
+        super(BackendLoader, self).setUp()
+
+        # TODO(blk-u): Shouldn't need to clear the registry here, but some
+        # tests call load_backends multiple times. These should be fixed to
+        # only call load_backends once.
+        dependency.reset()
+
+        # TODO(morganfainberg): Shouldn't need to clear the registry here, but
+        # some tests call load_backends multiple times.  Since it is not
+        # possible to re-configure a backend, we need to clear the list.  This
+        # should eventually be removed once testing has been cleaned up.
+        kvs_core.KEY_VALUE_STORE_REGISTRY.clear()
+
+        self.clear_auth_plugin_registry()
+        drivers, _unused = common.setup_backends()
+
+        for manager_name, manager in drivers.items():
+            setattr(self._testcase, manager_name, manager)
+
+        self.addCleanup(self._testcase.cleanup_instance(*list(drivers.keys())))
+
+        del self._testcase  # break circular reference
+
+    def clear_auth_plugin_registry(self):
+        auth.controllers.AUTH_METHODS.clear()
+        auth.controllers.AUTH_PLUGINS_LOADED = False