code: def test_reader_chunk_removal(tmpdir):
      cache_dir = os.path.join(tmpdir, "cache_dir")
      remote_dir = os.path.join(tmpdir, "remote_dir")
      os.makedirs(cache_dir, exist_ok=True)
      cache = Cache(
          input_dir=Dir(path=cache_dir, url=remote_dir),
          chunk_size=2,
          max_cache_size=28020,
      )
  
      for i in range(25):
          cache[i] = i
  
      cache.done()
      cache.merge()
  
      shutil.copytree(cache_dir, remote_dir)
      shutil.rmtree(cache_dir)
      os.makedirs(cache_dir, exist_ok=True)
  
      for i in range(25):
          index = ChunkedIndex(
              i,
              cache._get_chunk_index_from_index(i),
              is_last_index=i == 24,
          )
          assert cache[index] == i
  
      assert len(os.listdir(cache_dir)) == 14
  
      cache = Cache(
          input_dir=Dir(path=cache_dir, url=remote_dir),
          chunk_size=2,
          max_cache_size=2800,
      )
  
      shutil.rmtree(cache_dir)
      os.makedirs(cache_dir, exist_ok=True)
  
      for i in range(25):
          assert len(os.listdir(cache_dir)) <= 3
          index = ChunkedIndex(
              i,
              cache._get_chunk_index_from_index(i),
              is_last_index=i == 24,
          )
          assert cache[index] == i
  
      assert len(os.listdir(cache_dir)) == 3
  
file_path: pytorch-lightning/tests/tests_data/streaming/test_reader.py
imports: import os
  import shutil
  from time import sleep
  import numpy
  from lightning.data.streaming import reader
  from lightning.data.streaming.cache import Cache
  from lightning.data.streaming.config import ChunkedIndex
  from lightning.data.streaming.item_loader import PyTreeLoader
  from lightning.data.streaming.reader import _END_TOKEN, PrepareChunksThread, _get_folder_size
  from lightning_cloud.resolver import Dir
label_desc: Use image node_id 1 for calling a global function with example usage: test_reader_chunk_removal(tmpdir) without return types