code: def testSingleLetterGroup(self):
      self.assertPlatformSpecificLogdirParsing(
          posixpath, "A:/foo/path", {"/foo/path": "A"}
      )
      # single letter groups are not supported on Windows
      with self.assertRaises(AssertionError):
          self.assertPlatformSpecificLogdirParsing(
              ntpath, "A:C:\\foo\\path", {"C:\\foo\\path": "A"}
          )
  
imports: import ntpath
  import os
  import posixpath
  import time
  from unittest import mock
  from tensorboard import test
  from tensorboard.backend.event_processing import data_ingester
  from tensorboard.compat import tf
label_desc: Use image node_id 15 for calling the ParseEventFilesSpecTest obj's underlying member method code with example usage: obj.testSingleLetterGroup() without return types