class_docstr: Subclass this class to create a GUI TestRunner that uses a specific
  windowing toolkit. The class takes care of running tests in the correct
  manner, and making callbacks to the derived class to obtain information
  or signal that events have occurred.
class_docstr_tok: ["Subclass","this","class","to","create","a","GUI","TestRunner","that","uses","a","specific","windowing","toolkit",".","The","class","takes","care","of","running","tests","in","the","correct","manner",",","and","making","callbacks","to","the","derived","class","to","obtain","information","or","signal","that","events","have","occurred","."]
code: def discoverClicked(self):
      self.__rollbackImporter.rollbackImports()
      directory = self.getDirectoryToDiscover()
      if not directory:
          return
      self.directory_to_read = directory
      try:
          # Explicitly use 'None' value if no top level directory is
          # specified (indicated by empty string) as discover() explicitly
          # checks for a 'None' to determine if no tld has been specified
          top_level_dir = self.top_level_dir or None
          tests = unittest.defaultTestLoader.discover(
              directory, self.test_file_glob_pattern, top_level_dir
          )
          self.test_suite = tests
      except:
          exc_type, exc_value, exc_tb = sys.exc_info()
          traceback.print_exception(*sys.exc_info())
          self.errorDialog(
              "Unable to run test '%s'" % directory,
              "Error loading specified test: %s, %s"
              % (exc_type, exc_value),
          )
          return
      self.notifyTestsDiscovered(self.test_suite)
  
imports: import sys
  import traceback
  import unittest
  import tkinter
  from tkinter import messagebox
  from tkinter import filedialog
  from tkinter import simpledialog
label_desc: Use image node_id 6 for calling the BaseGUITestRunner obj's underlying member method code with example usage: obj.discoverClicked() without return types