Revert "Removed test_lib module"

This reverts commit 9a6536de6e.

We pulled all of the plugins out of the tree, many of which still inherit
from neutron test classes. This change then stated that we no longer
support testing other plugins. I think this is a bit premature and should
have been discussed under the subject 
"Neutron plugins can't use neutron plugin unit tests" or something
similar.

Change-Id: I68318589f010b731574ea3bfa8df98492bab31fc

neutron/common/test_lib.py

@@ -0,0 +1,42 @@
+# Copyright (c) 2010 OpenStack Foundation
+# 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.
+
+# Colorizer Code is borrowed from Twisted:
+# Copyright (c) 2001-2010 Twisted Matrix Laboratories.
+#
+#    Permission is hereby granted, free of charge, to any person obtaining
+#    a copy of this software and associated documentation files (the
+#    "Software"), to deal in the Software without restriction, including
+#    without limitation the rights to use, copy, modify, merge, publish,
+#    distribute, sublicense, and/or sell copies of the Software, and to
+#    permit persons to whom the Software is furnished to do so, subject to
+#    the following conditions:
+#
+#    The above copyright notice and this permission notice shall be
+#    included in all copies or substantial portions of the Software.
+#
+#    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+#    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+#    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+#    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+#    LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+#    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+#    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+# describes parameters used by different unit/functional tests
+# a plugin-specific testing mechanism should import this dictionary
+# and override the values in it if needed (e.g., run_tests.py in
+# neutron/plugins/openvswitch/ )
+test_config = {}

neutron/tests/unit/db/test_db_base_plugin_v2.py

@@ -22,6 +22,7 @@ import netaddr
 from oslo_config import cfg
 from oslo_db import exception as db_exc
 from oslo_utils import importutils
+import six
 from sqlalchemy import orm
 from testtools import matchers
 import webob.exc
@@ -36,6 +37,7 @@ from neutron.callbacks import registry
 from neutron.common import constants
 from neutron.common import exceptions as n_exc
 from neutron.common import ipv6_utils
+from neutron.common import test_lib
 from neutron.common import utils
 from neutron import context
 from neutron.db import db_base_plugin_v2
@@ -104,8 +106,11 @@ class NeutronDbPluginV2TestCase(testlib_api.WebTestCase):
 
         # Update the plugin
         self.setup_coreplugin(plugin)
-        service_plugins = (service_plugins or {}).values()
-        cfg.CONF.set_override('service_plugins', list(service_plugins))
+        cfg.CONF.set_override(
+            'service_plugins',
+            [test_lib.test_config.get(key, default)
+             for key, default in six.iteritems(service_plugins or {})]
+        )
 
         cfg.CONF.set_override('base_mac', "12:34:56:78:90:ab")
         cfg.CONF.set_override('max_dns_nameservers', 2)
@@ -157,6 +162,14 @@ class NeutronDbPluginV2TestCase(testlib_api.WebTestCase):
         self.ext_api = None
         super(NeutronDbPluginV2TestCase, self).tearDown()
 
+    def setup_config(self):
+        # Create the default configurations
+        args = ['--config-file', base.etcdir('neutron.conf')]
+        # If test_config specifies some config-file, use it, as well
+        for config_file in test_lib.test_config.get('config_files', []):
+            args.extend(['--config-file', config_file])
+        super(NeutronDbPluginV2TestCase, self).setup_config(args=args)
+
     def _req(self, method, resource, data=None, fmt=None, id=None, params=None,
              action=None, subresource=None, sub_id=None, context=None):
         fmt = fmt or self.fmt