class_docstr: Test selecting key on Basic frames.
class_docstr_tok: ["Test","selecting","key","on","Basic","frames","."]
code: def tearDownClass(cls):
      del cls.dialog
      cls.root.update_idletasks()
      cls.root.destroy()
      del cls.root
  
imports: from idlelib import config_key
  from test.support import requires
  import unittest
  from unittest import mock
  from tkinter import Tk, TclError
  from idlelib.idle_test.mock_idle import Func
  from idlelib.idle_test.mock_tk import Mbox_func
label_desc: Use image node_id 2 for calling the KeySelectionTest obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types