code: def test_readline(self):
      shell = MockShell()
      f = run.StdInputFile(shell, "stdin")
      shell.push(["one\n", "two\n", "three\n", "four\n"])
      self.assertEqual(f.readline(), "one\n")
      self.assertEqual(f.readline(-1), "two\n")
      self.assertEqual(f.readline(None), "three\n")
      shell.push(["one\ntwo\n"])
      self.assertEqual(f.readline(), "one\n")
      self.assertEqual(f.readline(), "two\n")
      shell.push(["one", "two", "three"])
      self.assertEqual(f.readline(), "one")
      self.assertEqual(f.readline(), "two")
      shell.push(["one\n", "two\n", "three\n"])
      self.assertEqual(f.readline(2), "on")
      self.assertEqual(f.readline(1), "e")
      self.assertEqual(f.readline(1), "\n")
      self.assertEqual(f.readline(10), "two\n")
  
      shell.push(["one\n", "two\n"])
      self.assertEqual(f.readline(0), "")
      self.assertRaises(TypeError, f.readlines, 1.5)
      self.assertRaises(TypeError, f.readlines, "1")
      self.assertRaises(TypeError, f.readlines, 1, 1)
  
imports: from idlelib import run
  import io
  import sys
  from test.support import captured_output, captured_stderr
  import unittest
  from unittest import mock
  import idlelib
  from idlelib.idle_test.mock_idle import Func
label_desc: Use image node_id 4 for calling the StdInputFilesTest obj's underlying member method code with example usage: obj.test_readline() without return types