code: def test_grayscale(
      grayscale_fn: Callable,
      input_img: torch.Tensor,
      grayscale_img: torch.Tensor,
  ):
      output_img = grayscale_fn(input_img)
      assert torch.equal(output_img, grayscale_img)
  
file_path: ludwig/tests/ludwig/utils/test_image_utils.py
imports: from typing import Callable
  import pytest
  import torch
  import torchvision.transforms.functional
  from ludwig.utils.image_utils import crop, crop_or_pad, grayscale, is_image_score, num_channels_in_image, pad, read_image_as_tif, resize_image, ResizeChannels
label_desc: Use image node_id 5 for calling a global function with example usage: test_grayscale(grayscale_fn, input_img, grayscale_img) without return types