code: def test_raises_400_if_manager_is_not_fab(
      self, mock_get_auth_manager
  ):
      mock_get_auth_manager.return_value = BaseAuthManager(
          self.app.appbuilder
      )
      response = self.client.get(
          "api/v1/roles", environ_overrides={"REMOTE_USER": "test"}
      )
      assert response.status_code == 400
      assert (
          response.json["detail"]
          == "This endpoint is only available when using the default auth manager FabAuthManager."
      )
  
imports: from __future__ import annotations
  from unittest import mock
  import pytest
  from airflow.auth.managers.base_auth_manager import BaseAuthManager
  from airflow.providers.fab.auth_manager.models import Role, User
  from airflow.security import permissions
  from airflow.utils import timezone
  from airflow.utils.session import create_session
  from airflow.www.security import EXISTING_ROLES
  from tests.test_utils.api_connexion_utils import create_role, create_user, delete_role, delete_user
label_desc: Use image node_id 1 for calling the TestFABRoleForwarding obj's underlying member method code with example usage: obj.test_raises_400_if_manager_is_not_fab(mock_get_auth_manager) without return types