text: # Copyright 2017 NEC Corporation.  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 time
  
  from oslo_serialization import jsonutils as json
  
  from tempest.lib.api_schema.response.volume import versions as schema
  from tempest.lib.common import rest_client
  from tempest.lib.services.volume import base_client
  
  
  class VersionsClient(base_client.BaseClient):
  
      def list_versions(self):
          """List API versions
  
          For a full list of available parameters, please refer to the official
          API reference:
          https://developer.openstack.org/api-ref/block-storage/v3/#list-all-api-versions
          """
          version_url = self._get_base_version_url()
  
          start = time.time()
          resp, body = self.raw_request(version_url, 'GET')
          end = time.time()
          # NOTE: We need a raw_request() here instead of request() call because
          # "list API versions" API doesn't require an authentication and we can
          # skip it with raw_request() call.
          self._log_request('GET', version_url, resp, secs=(end - start),
                            resp_body=body)
          self._error_checker(resp, body)
  
          body = json.loads(body)
          self.validate_response(schema.list_versions, resp, body)
          return rest_client.ResponseBody(resp, body)
  