code: def test_trns_rgb(self):
      # Check writing and reading of tRNS chunks for RGB images.
      # Independent file sample provided by Sebastian Spaeth.
  
      test_file = "Tests/images/caption_6_33_22.png"
      with Image.open(test_file) as im:
          assert im.info["transparency"] == (248, 248, 248)
  
          # check saving transparency by default
          im = roundtrip(im)
      assert im.info["transparency"] == (248, 248, 248)
  
      im = roundtrip(im, transparency=(0, 1, 2))
      assert im.info["transparency"] == (0, 1, 2)
  
imports: from __future__ import annotations
  import re
  import sys
  import warnings
  import zlib
  from io import BytesIO
  import pytest
  from PIL import Image, ImageFile, PngImagePlugin, features
  from .helper import PillowLeakTestCase, assert_image, assert_image_equal, assert_image_equal_tofile, hopper, is_win32, mark_if_feature_version, skip_unless_feature
label_desc: Use image node_id 27 for calling the TestFilePng obj's underlying member method code with example usage: obj.test_trns_rgb() without return types