Added a base class for unit tests.

This provides some basic cfg and subout infrastructure
for tests.  It's similar to the test base used in
other OpenStack projects, so having it here should make
migrating tests to common somewhat easier.

Change-Id: I90775bf99313e7dd16929059132ee058287b3585

tests/utils.py

@@ -0,0 +1,56 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010-2011 OpenStack, LLC
+# All Rights Reserved.
+#
+#    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.
+
+"""Common utilities used in testing"""
+
+import stubout
+import subprocess
+import unittest
+
+from openstack.common import cfg
+
+CONF = cfg.CONF
+
+
+class BaseTestCase(unittest.TestCase):
+
+    def setUp(self):
+        super(BaseTestCase, self).setUp()
+        self.stubs = stubout.StubOutForTesting()
+
+    def tearDown(self):
+        super(BaseTestCase, self).tearDown()
+        CONF.reset()
+        self.stubs.UnsetAll()
+        self.stubs.SmartUnsetAll()
+
+    def config(self, **kw):
+        """
+        Override some configuration values.
+
+        The keyword arguments are the names of configuration options to
+        override and their values.
+
+        If a group argument is supplied, the overrides are applied to
+        the specified configuration option group.
+
+        All overrides are automatically cleared at the end of the current
+        test by the tearDown() method.
+        """
+        group = kw.pop('group', None)
+        for k, v in kw.iteritems():
+            CONF.set_override(k, v, group)