text: # Copyright 2012 OpenStack Foundation
  #
  # 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 uuid
  
  from keystone.common import manager
  from keystone.common import provider_api
  from keystone.tests import unit
  
  
  class TestProviderAPIRegistry(unit.BaseTestCase):
      def setUp(self):
          super(TestProviderAPIRegistry, self).setUp()
          provider_api.ProviderAPIs._clear_registry_instances()
          self.addCleanup(provider_api.ProviderAPIs._clear_registry_instances)
  
      def _create_manager_instance(self, provides_api=None):
          provides_api = provides_api or '%s_api' % uuid.uuid4().hex
  
          class TestManager(manager.Manager):
              _provides_api = provides_api
              driver_namespace = '_TEST_NOTHING'
  
              def do_something(self):
                  return provides_api
  
          return TestManager(driver_name=None)
  
      def test_deferred_gettr(self):
          api_name = '%s_api' % uuid.uuid4().hex
  
          class TestClass(object):
              descriptor = provider_api.ProviderAPIs.deferred_provider_lookup(
                  api=api_name, method='do_something')
  
          test_instance = TestClass()
          # Accessing the descriptor will raise the known "attribute" error
          self.assertRaises(AttributeError, getattr, test_instance, 'descriptor')
          self._create_manager_instance(provides_api=api_name)
          # once the provider has been instantiated, we can call the descriptor
          # which will return the method (callable) and we can check that the
          # return value is as expected.
          self.assertEqual(api_name, test_instance.descriptor())
  
      def test_registry_lock(self):
          provider_api.ProviderAPIs.lock_provider_registry()
          self.assertRaises(RuntimeError, self._create_manager_instance)
  
      def test_registry_duplicate(self):
          test_manager = self._create_manager_instance()
          self.assertRaises(
              provider_api.DuplicateProviderError,
              self._create_manager_instance,
              provides_api=test_manager._provides_api)
  
      def test_provider_api_mixin(self):
          test_manager = self._create_manager_instance()
  
          class Testing(provider_api.ProviderAPIMixin, object):
              pass
  
          instance = Testing()
          self.assertIs(test_manager, getattr(instance,
                                              test_manager._provides_api))
  
      def test_manager_api_reference(self):
          manager = self._create_manager_instance()
          second_manager = self._create_manager_instance()
          self.assertIs(second_manager, getattr(manager,
                                                second_manager._provides_api))
          self.assertIs(manager, getattr(second_manager,
                                         manager._provides_api))
  