rehome the resource_extend db module
This patch rehomes neutron.db._resource_extend into neutron-lib. While the module is private in neutron, it's used by consumers today [1]. The patch also includes a test fixture along with unit tests and a release note. [1] http://codesearch.openstack.org/?q=from%20neutron%5C.db%20import%20_resource_extend&i=nope&files=&repos= Change-Id: I2306ba92dcf4a989c7c73e5f0ef4bfb4f804b6cd
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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NOTE: This module shall not be used by external projects. It will be moved
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to neutron-lib in due course, and then it can be used from there.
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"""
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import collections
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import inspect
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from neutron_lib.utils import helpers
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# This dictionary will store methods for extending API resources.
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# Extensions can add their own methods by invoking register_funcs().
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_resource_extend_functions = {
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# <resource1> : [<func1>, <func2>, ...],
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# <resource2> : [<func1>, <func2>, ...],
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# ...
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}
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# This dictionary will store @extends decorated methods with a list of
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# resources that each method will extend on class initialization.
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_DECORATED_EXTEND_METHODS = collections.defaultdict(list)
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_DECORATED_METHODS_REGISTERED = '_DECORATED_METHODS_REGISTERED'
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def register_funcs(resource, funcs):
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"""Add functions to extend a resource.
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:param resource: A resource collection name.
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:type resource: str
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:param funcs: A list of functions.
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:type funcs: list of callable
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These functions take a resource dict and a resource object and
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update the resource dict with extension data (possibly retrieved
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from the resource db object).
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def _extend_foo_with_bar(foo_res, foo_db):
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foo_res['bar'] = foo_db.bar_info # example
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return foo_res
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"""
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funcs = [helpers.make_weak_ref(f) if callable(f) else f
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for f in funcs]
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_resource_extend_functions.setdefault(resource, []).extend(funcs)
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def get_funcs(resource):
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"""Retrieve a list of functions extending a resource.
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:param resource: A resource collection name.
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:type resource: str
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:return: A list (possibly empty) of functions extending resource.
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:rtype: list of callable
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"""
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return _resource_extend_functions.get(resource, [])
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def apply_funcs(resource_type, response, db_object):
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"""Appy registered functions for the said resource type.
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:param resource_type: The resource type to apply funcs for.
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:param response: The response object.
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:param db_object: The Database object.
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:returns: None
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"""
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for func in get_funcs(resource_type):
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resolved_func = helpers.resolve_ref(func)
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if resolved_func:
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resolved_func(response, db_object)
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def extends(resources):
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"""Use to decorate methods on classes before initialization.
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Any classes that use this must themselves be decorated with the
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@has_resource_extenders decorator to setup the __new__ method to
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actually register the instance methods after initialization.
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:param resources: Resource collection names. The decorated method will
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be registered with each resource as an extend function.
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:type resources: list of str
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"""
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def decorator(method):
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_DECORATED_EXTEND_METHODS[method].extend(resources)
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return method
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return decorator
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def has_resource_extenders(klass):
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"""Decorator to setup __new__ method in classes to extend resources.
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Any method decorated with @extends above is an unbound method on a class.
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This decorator sets up the class __new__ method to add the bound
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method to _resource_extend_functions after object instantiation.
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"""
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orig_new = klass.__new__
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new_inherited = '__new__' not in klass.__dict__
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@staticmethod
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def replacement_new(cls, *args, **kwargs):
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if new_inherited:
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# class didn't define __new__ so we need to call inherited __new__
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super_new = super(klass, cls).__new__
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if super_new is object.__new__:
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# object.__new__ doesn't accept args nor kwargs
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instance = super_new(cls)
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else:
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instance = super_new(cls, *args, **kwargs)
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else:
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instance = orig_new(cls, *args, **kwargs)
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if getattr(instance, _DECORATED_METHODS_REGISTERED, False):
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# Avoid running this logic twice for classes inheriting other
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# classes with this same decorator. Only one needs to execute
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# to subscribe all decorated methods.
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return instance
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for name, unbound_method in inspect.getmembers(cls):
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if (not inspect.ismethod(unbound_method) and
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not inspect.isfunction(unbound_method)):
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continue
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# Handle py27/py34 difference
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method = getattr(unbound_method, 'im_func', unbound_method)
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if method not in _DECORATED_EXTEND_METHODS:
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continue
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for resource in _DECORATED_EXTEND_METHODS[method]:
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# Register the bound method for the resourse
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register_funcs(resource, [method])
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setattr(instance, _DECORATED_METHODS_REGISTERED, True)
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return instance
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klass.__new__ = replacement_new
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return klass
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@ -24,6 +24,7 @@ from neutron_lib.callbacks import registry
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from neutron_lib.db import api as db_api
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from neutron_lib.db import model_base
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from neutron_lib.db import model_query
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from neutron_lib.db import resource_extend
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from neutron_lib.plugins import directory
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from neutron_lib import rpc
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from neutron_lib.tests.unit import fake_notifier
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self.addCleanup(rpc.cleanup)
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rpc.init(CONF)
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class DBResourceExtendFixture(fixtures.Fixture):
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def __init__(self, extended_methods=None):
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self.extended_methods = extended_methods or {}
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def _setUp(self):
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self._backup = copy.deepcopy(
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resource_extend._DECORATED_EXTEND_METHODS)
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resource_extend._DECORATED_EXTEND_METHODS = self.extended_methods
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self.addCleanup(self._restore)
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def _restore(self):
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resource_extend._DECORATED_EXTEND_METHODS = self._backup
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@ -0,0 +1,65 @@
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from oslotest import base
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from neutron_lib.db import resource_extend
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from neutron_lib import fixture
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@resource_extend.has_resource_extenders
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class _DBExtender(object):
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@resource_extend.extends('ExtendedA')
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def _extend_a(self, resp, db_obj):
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pass
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@resource_extend.extends('ExtendedB')
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def _extend_b(self, resp, db_obj):
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pass
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class TestResourceExtendClass(base.BaseTestCase):
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def test_extends(self):
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self.assertIsNotNone(resource_extend.get_funcs('ExtendedA'))
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self.assertIsNotNone(resource_extend.get_funcs('ExtendedB'))
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class TestResourceExtend(base.BaseTestCase):
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def setUp(self):
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super(TestResourceExtend, self).setUp()
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self.useFixture(fixture.DBResourceExtendFixture())
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def test_register_funcs(self):
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resources = ['A', 'B', 'C']
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for r in resources:
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resource_extend.register_funcs(r, (lambda x: x,))
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for r in resources:
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self.assertIsNotNone(resource_extend.get_funcs(r))
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def test_apply_funcs(self):
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resources = ['A', 'B', 'C']
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callbacks = []
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def _cb(resp, db_obj):
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callbacks.append(resp)
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for r in resources:
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resource_extend.register_funcs(r, (_cb,))
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for r in resources:
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resource_extend.apply_funcs(r, None, None)
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self.assertEqual(3, len(callbacks))
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from neutron_lib.api.definitions import port
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from neutron_lib.callbacks import registry
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from neutron_lib.db import model_base
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from neutron_lib.db import resource_extend
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from neutron_lib import fixture
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from neutron_lib.placement import client as place_client
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from neutron_lib.plugins import directory
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p_client, p_fixture = self._create_client_and_fixture()
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p_client.list_aggregates('resource')
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p_fixture.mock_get.assert_called_once()
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class DBResourceExtendFixtureTestCase(base.BaseTestCase):
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def test_fixture_backup(self):
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fake_methods = {
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'a': 'A',
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'b': 'B'
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}
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orig_methods = resource_extend._DECORATED_EXTEND_METHODS
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self.assertNotEqual(fake_methods, orig_methods)
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db_fixture = fixture.DBResourceExtendFixture(
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extended_methods=fake_methods)
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db_fixture.setUp()
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resource_extend.register_funcs('C', (lambda x: x,))
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self.assertNotEqual(
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orig_methods, resource_extend._DECORATED_EXTEND_METHODS)
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db_fixture.cleanUp()
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self.assertEqual(
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orig_methods, resource_extend._DECORATED_EXTEND_METHODS)
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@ -0,0 +1,6 @@
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---
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features:
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- The ``neutron.db._resource_extend`` is now available as
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``neutron_lib.db.resource_extend`` along with a new
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``DBResourceExtendFixture`` that allows tests to modify the
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map of registered resource functions.
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