code: def test_connections_prefix_none_value(
      self, mock_client_callable, mock_get_creds
  ):
      mock_get_creds.return_value = CREDENTIALS, PROJECT_ID
      mock_client = mock.MagicMock()
      mock_client_callable.return_value = mock_client
  
      with mock.patch(
          MODULE_NAME + ".CloudSecretManagerBackend._get_secret"
      ) as mock_get_secret:
          with mock.patch(
              MODULE_NAME
              + ".CloudSecretManagerBackend._is_valid_prefix_and_sep"
          ) as mock_is_valid_prefix_sep:
              secrets_manager_backend = CloudSecretManagerBackend(
                  connections_prefix=None
              )
  
              mock_is_valid_prefix_sep.assert_not_called()
              assert (
                  secrets_manager_backend.get_conn_uri(conn_id=CONN_ID)
                  is None
              )
              mock_get_secret.assert_not_called()
  
imports: from __future__ import annotations
  import logging
  import re
  from unittest import mock
  import pytest
  from google.api_core.exceptions import NotFound
  from google.cloud.secretmanager_v1.types import AccessSecretVersionResponse
  from airflow.exceptions import AirflowException
  from airflow.models import Connection
  from airflow.providers.google.cloud.secrets.secret_manager import CloudSecretManagerBackend
label_desc: Use image node_id 11 for calling the TestCloudSecretManagerBackend obj's underlying member method code with example usage: obj.test_connections_prefix_none_value(mock_client_callable, mock_get_creds) without return types