code: def test_autocontrast_preserve_one_color(color):
      img = Image.new("RGB", (10, 10), color)
  
      # single color images shouldn't change
      out = ImageOps.autocontrast(img, cutoff=0, preserve_tone=True)
      assert_image_equal(img, out)  # single color, no cutoff
  
      # even if there is a cutoff
      out = ImageOps.autocontrast(
          img, cutoff=10, preserve_tone=True
      )  # single color 10 cutoff
      assert_image_equal(img, out)
  
imports: from __future__ import annotations
  import pytest
  from PIL import Image, ImageDraw, ImageOps, ImageStat, features
  from .helper import assert_image_equal, assert_image_similar, assert_image_similar_tofile, assert_tuple_approx_equal, hopper
label_desc: Use image node_id 24 for calling a global function with example usage: test_autocontrast_preserve_one_color(color) without return types