code: def test_save_fp():
      fp = io.BytesIO()
  
      with Image.open(TEST_FILE) as im:
          im.save(fp, format="ICNS")
  
      with Image.open(fp) as reread:
          assert reread.mode == "RGBA"
          assert reread.size == (1024, 1024)
          assert reread.format == "ICNS"
  
file_path: pillow-simd/Tests/test_file_icns.py
imports: import io
  import os
  import pytest
  from PIL import IcnsImagePlugin, Image, _binary, features
  from .helper import assert_image_equal, assert_image_similar_tofile
label_desc: Use image node_id 4 for calling a global function with example usage: test_save_fp() without return types