code: def test_tensor_cache(self):
      cache = TensorCache(self.TEST_DIR / "cache")
      assert not cache.read_only
  
      # Insert some stuff into the cache.
      cache["a"] = torch.tensor([1, 2, 3])
  
      # Close cache.
      del cache
  
      # Now let's open another one in read-only mode.
      cache = TensorCache(self.TEST_DIR / "cache", read_only=True)
      assert cache.read_only
  
      # If we try to write we should get a ValueError
      with pytest.raises(ValueError, match="cannot write"):
          cache["b"] = torch.tensor([1, 2, 3])
  
      # But we should be able to retrieve from the cache.
      assert cache["a"].shape == (3,)
  
      # Close this one.
      del cache
  
      # Now we're going to tell the OS to make the cache file read-only.
      os.chmod(self.TEST_DIR / "cache", 0o444)
      os.chmod(self.TEST_DIR / "cache-lock", 0o444)
  
      # This time when we open the cache, it should automatically be set to read-only.
      with pytest.warns(UserWarning, match="cache will be read-only"):
          cache = TensorCache(self.TEST_DIR / "cache")
          assert cache.read_only
  
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 1 for calling the TestTensorCache obj's underlying member method code with example usage: obj.test_tensor_cache() without return types