code: def test_view_file(self):
      view = tv.view_file(root, "Title", __file__, "ascii", modal=False)
      self.assertIsInstance(view, tv.ViewWindow)
      self.assertIsInstance(view.viewframe, tv.ViewFrame)
      get = view.viewframe.textframe.text.get
      self.assertIn("Test", get("1.0", "1.end"))
      view.ok()
  
imports: from idlelib import textview
  from test.support import requires
  import os
  import unittest
  from tkinter import Tk, TclError, CHAR, NONE, WORD
  from tkinter.ttk import Button
  from idlelib.idle_test.mock_idle import Func
  from idlelib.idle_test.mock_tk import Mbox_func
label_desc: Use image node_id 4 for calling the ViewFunctionTest obj's underlying member method code with example usage: obj.test_view_file() without return types