Add WebTest as dependency for testing

Latest pecan release dropped this dependency. This is why now it is
needed to explicitly install it during testing.

This patch also registers the Neutron core common config options in
``TaasExtensionTestCase``. Since [1], the configuration options
must be explicitly loaded.

[1]https://review.opendev.org/c/openstack/neutron/+/837392

Closes-Bug: #1982110
Change-Id: I3d8cd840881a2c67e7b07458276d600e214d028e

neutron_taas/tests/unit/extensions/test_taas.py

@@ -19,6 +19,7 @@ from webob import exc
 from oslo_utils import uuidutils
 
 from neutron.api import extensions
+from neutron.conf import common as conf_common
 from neutron.tests.unit.api.v2 import test_base as test_api_v2
 from neutron.tests.unit.extensions import base as test_extensions_base
 from neutron_lib.api.definitions import taas as taas_api
@@ -35,6 +36,7 @@ TAP_FLOW_PATH = 'taas/tap_flows'
 class TaasExtensionTestCase(test_extensions_base.ExtensionTestCase):
 
     def setUp(self):
+        conf_common.register_core_common_config_opts()
         extensions.append_api_extensions_path(taas_extensions.__path__)
         super(TaasExtensionTestCase, self).setUp()
         plural_mappings = {'tap_service': 'tap_services',

test-requirements.txt

@@ -21,3 +21,4 @@ mock>=3.0.0 # BSD
 astroid==2.1.0 # LGPLv2.1
 pylint==2.2.0 # GPLv2
 isort==4.3.21 # MIT
+WebTest>=2.0.27 # MIT