code: def test_should_read_connection(self, tmp_path):
      path = tmp_path / "testfile.env"
      path.write_text("CONN_A=mysql://host_a")
      backend = LocalFilesystemBackend(
          connections_file_path=os.fspath(path)
      )
      assert (
          "mysql://host_a" == backend.get_connection("CONN_A").get_uri()
      )
      assert backend.get_variable("CONN_B") is None
  
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 3 for calling the TestLocalFileBackend obj's underlying member method code with example usage: obj.test_should_read_connection(tmp_path) without return types