code: def test_tensor_cache_upgrade(self):
      cache0 = TensorCache(self.TEST_DIR / "upcache")
      cache0["foo"] = torch.tensor([1, 2, 3])
      del cache0
  
      cache1 = TensorCache(self.TEST_DIR / "upcache", read_only=True)
      cache2 = TensorCache(self.TEST_DIR / "upcache")
      assert not cache1.read_only
      assert not cache2.read_only
      assert torch.allclose(cache1["foo"], torch.tensor([1, 2, 3]))
  
      cache2["bar"] = torch.tensor([2, 3, 4])
      assert torch.allclose(cache1["bar"], cache2["bar"])
  
imports: import os
  import pathlib
  import json
  import time
  import shutil
  from filelock import Timeout
  import pytest
  import responses
  import torch
  from allennlp.common.file_utils import FileLock, _resource_to_filename, filename_to_url, cached_path, open_compressed, CacheFile, _Meta, _find_entries, inspect_cache, remove_cache_entries, LocalCacheResource, TensorCache
  from allennlp.common import Params
  from allennlp.modules.token_embedders import ElmoTokenEmbedder
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.predictors import Predictor
label_desc: Use image node_id 3 for calling the TestTensorCache obj's underlying member method code with example usage: obj.test_tensor_cache_upgrade() without return types