class_docstr: Test the config system.
class_docstr_tok: ["Test","the","config","system","."]
code: def test_server_headless(self):
      orig_display = None
      if "DISPLAY" in os.environ.keys():
          orig_display = os.environ["DISPLAY"]
          del os.environ["DISPLAY"]
  
      orig_is_linux_or_bsd = env_util.IS_LINUX_OR_BSD
      env_util.IS_LINUX_OR_BSD = True
  
      self.assertEqual(True, config.get_option("server.headless"))
  
      env_util.IS_LINUX_OR_BSD = orig_is_linux_or_bsd
      if orig_display:
          os.environ["DISPLAY"] = orig_display
  
imports: import copy
  import os
  import textwrap
  import unittest
  from unittest.mock import MagicMock, mock_open, patch
  import pytest
  from parameterized import parameterized
  from streamlit import config, env_util
  from streamlit.config_option import ConfigOption
  from streamlit.errors import StreamlitAPIException
label_desc: Use image node_id 34 for calling the ConfigTest obj's underlying member method code with example usage: obj.test_server_headless() without return types