code: def test_docline_truncation(self):
      def f():
          pass
  
      f.__doc__ = "a" * 300
      self.assertEqual(
          get_spec(f), f"()\n{'a'*(calltip._MAX_COLS-3) + '...'}"
      )
  
imports: from idlelib import calltip
  import unittest
  from unittest.mock import Mock
  import textwrap
  import types
  import re
  from idlelib.idle_test.mock_tk import Text
  from test.support import MISSING_C_DOCSTRINGS
label_desc: Use image node_id 4 for calling the Get_argspecTest obj's underlying member method code with example usage: obj.test_docline_truncation() without return types