code: def test_result_none_error(self):
      @cache_results("demo.pkl")
      def cache():
          pass
  
      try:
          with pytest.raises(RuntimeError):
              results = cache()
      finally:
          rank_zero_rm("demo.pkl")
  
imports: import os
  import pytest
  import subprocess
  from io import StringIO
  import sys
  from fastNLP.core.utils.cache_results import cache_results
  from fastNLP.envs.distributed import rank_zero_rm
label_desc: Use image node_id 10 for calling the TestCacheResults obj's underlying member method code with example usage: obj.test_result_none_error() without return types