code: def test_load_secret_backend_LocalFilesystemBackend(self):
      with mock_local_file("KEY_A=VAL_A"):
          backends = ensure_secrets_loaded()
  
          backend_classes = [
              backend.__class__.__name__ for backend in backends
          ]
          assert "LocalFilesystemBackend" in backend_classes
          assert Variable.get("KEY_A") == "VAL_A"
  
imports: from __future__ import annotations
  import json
  import os
  import re
  from contextlib import contextmanager
  from unittest import mock
  import pytest
  from airflow.configuration import ensure_secrets_loaded
  from airflow.exceptions import AirflowException, AirflowFileParseException, ConnectionNotUnique
  from airflow.models import Variable
  from airflow.secrets import local_filesystem
  from airflow.secrets.local_filesystem import LocalFilesystemBackend
  from tests.test_utils.config import conf_vars
label_desc: Use image node_id 2 for calling the TestLocalFileBackend obj's underlying member method code with example usage: obj.test_load_secret_backend_LocalFilesystemBackend() without return types