old_contents: # Copyright 2016 AT&T Corp
  # 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.
  
  import webob
  
  from murano.api import versions
  
  from murano.api.middleware import version_negotiation
  
  from murano.tests.unit import base
  
  
  class MiddlewareVersionNegotiationTest(base.MuranoTestCase):
  
      def test_middleware_version_negotiation_default(self):
          middleware_vn = version_negotiation.VersionNegotiationFilter(None)
          request = webob.Request.blank('/environments')
          result = middleware_vn.process_request(request)
          self.assertTrue(isinstance(result, versions.Controller))
  
new_contents: # Copyright 2016 AT&T Corp
  # 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.
  
  import webob
  
  from murano.api import versions
  
  from murano.api.middleware import version_negotiation
  
  from murano.tests.unit import base
  
  
  class MiddlewareVersionNegotiationTest(base.MuranoTestCase):
  
      def test_middleware_version_negotiation_default(self):
          middleware_vn = version_negotiation.VersionNegotiationFilter(None)
          request = webob.Request.blank('/environments')
          result = middleware_vn.process_request(request)
          self.assertIsInstance(result, versions.Controller)
  
subject: Change assertTrue(isinstance()) by optimal assert