code: def test_dataset_cache_recreation(tmpdir):
      """Test that we recreate the cache and other objects only when appropriate."""
      cache = Cache(str(tmpdir), chunk_size=10)
      for i in range(10):
          cache[i] = i
      cache.done()
      cache.merge()
  
      # repated `len()` calls
      dataset = StreamingDataset(input_dir=str(tmpdir))
      assert not dataset.cache
      assert not dataset.shuffler
      len(dataset)
      assert not dataset.cache
      shuffler = dataset.shuffler
      assert isinstance(shuffler, NoShuffle)
      len(dataset)
      assert dataset.shuffler is shuffler
  
      # repeated `iter()` calls
      dataset = StreamingDataset(input_dir=str(tmpdir))
      assert not dataset.cache
      assert not dataset.shuffler
      iter(dataset)
      cache = dataset.cache
      shuffler = dataset.shuffler
      assert isinstance(cache, Cache)
      assert isinstance(shuffler, NoShuffle)
      iter(dataset)
      assert isinstance(dataset.cache, Cache)
      assert isinstance(dataset.shuffler, NoShuffle)
      assert dataset.cache is not cache  # cache gets recreated
      assert dataset.shuffler is not shuffler  # shuffler gets recreated
  
      # repeated `getitem()` calls
      dataset = StreamingDataset(input_dir=str(tmpdir))
      assert not dataset.cache
      assert not dataset.shuffler
      _ = dataset[0]
      cache = dataset.cache
      shuffler = dataset.shuffler
      assert isinstance(cache, Cache)
      assert isinstance(shuffler, NoShuffle)
      _ = dataset[1]
      assert dataset.cache is cache  # cache gets reused
      assert dataset.shuffler is shuffler
  
imports: import os
  import sys
  from time import sleep
  from unittest import mock
  import numpy
  import pytest
  import torch
  from lightning import seed_everything
  from lightning.data.streaming import Cache, functions
  from lightning.data.streaming.dataloader import StreamingDataLoader
  from lightning.data.streaming.dataset import _INDEX_FILENAME, Dir, RemoteDir, StreamingDataset, _associate_chunks_to_workers, _replay_chunks_sampling, _replay_sampling, _should_replace_path, _try_create_cache_dir
  from lightning.data.streaming.item_loader import TokensLoader
  from lightning.data.streaming.shuffle import FullShuffle, NoShuffle
  from lightning.data.utilities.env import Environment, _DistributedEnv, _WorkerEnv
  from torch.utils.data import DataLoader
label_desc: Use image node_id 7 for calling a global function with example usage: test_dataset_cache_recreation(tmpdir) without return types