code: def test_upload_fn(tmpdir):
      input_dir = os.path.join(tmpdir, "input_dir")
      os.makedirs(input_dir, exist_ok=True)
  
      cache_dir = os.path.join(tmpdir, "cache_dir")
      os.makedirs(cache_dir, exist_ok=True)
  
      remote_output_dir = os.path.join(tmpdir, "remote_output_dir")
      os.makedirs(remote_output_dir, exist_ok=True)
  
      filepath = os.path.join(input_dir, "a.txt")
  
      with open(filepath, "w") as f:
          f.write("HERE")
  
      upload_queue = mock.MagicMock()
  
      paths = [filepath, None]
  
      def fn(*_, **__):
          value = paths.pop(0)
          if value is None:
              return value
          return value
  
      upload_queue.get = fn
  
      remove_queue = mock.MagicMock()
  
      assert os.listdir(remote_output_dir) == []
  
      _upload_fn(
          upload_queue,
          remove_queue,
          cache_dir,
          Dir(path=remote_output_dir, url=remote_output_dir),
      )
  
      assert os.listdir(remote_output_dir) == ["a.txt"]
  
imports: import os
  import random
  import sys
  from typing import Any, List
  from unittest import mock
  import lightning_cloud
  import numpy
  import pytest
  import torch
  from lightning import seed_everything
  from lightning.data.streaming import data_processor
  from lightning.data.streaming import functions
  from lightning.data.streaming.cache import Cache, Dir
  from lightning.data.streaming.data_processor import DataChunkRecipe, DataProcessor, DataTransformRecipe, _download_data_target, _get_item_filesizes, _map_items_to_workers_sequentially, _map_items_to_workers_weighted, _remove_target, _upload_fn, _wait_for_disk_usage_higher_than_threshold, _wait_for_file_to_exist
  from lightning.data.streaming.functions import LambdaDataTransformRecipe, map, optimize
  from lightning_cloud import resolver
  from lightning_utilities.core.imports import RequirementCache
label_desc: Use image node_id 1 for calling a global function with example usage: test_upload_fn(tmpdir) and returns: value, value