docstr: Test variable_set command
docstr_tok: ["Test","variable_set","command"]
code: def test_variables_set(self):
      """Test variable_set command"""
      variable_command.variables_set(
          self.parser.parse_args(["variables", "set", "foo", "bar"])
      )
      assert Variable.get("foo") is not None
      with pytest.raises(KeyError):
          Variable.get("foo1")
  
imports: from __future__ import annotations
  import os
  from contextlib import redirect_stdout
  from io import StringIO
  import pytest
  from sqlalchemy import select
  from airflow import models
  from airflow.cli import cli_parser
  from airflow.cli.commands import variable_command
  from airflow.models import Variable
  from airflow.utils.session import create_session
  from tests.test_utils.db import clear_db_variables
label_desc: Use image node_id 4 for calling the TestCliVariables obj's underlying member method code with example usage: obj.test_variables_set() without return types