code: def test_not_found_characters(self):
      self.ph = ESpeak("en-us")
      tokenizer_local = TTSTokenizer(
          use_phonemes=True,
          characters=IPAPhonemes(),
          phonemizer=self.ph,
      )
      self.assertEqual(len(self.tokenizer.not_found_characters), 0)
      text = "Yolk of one egg beaten light"
      ids = tokenizer_local.text_to_ids(text)
      text_hat = tokenizer_local.ids_to_text(ids)
      self.assertEqual(tokenizer_local.not_found_characters, ["̩"])
      self.assertEqual(text_hat, "jˈoʊk ʌv wˈʌn ˈɛɡ bˈiːʔn lˈaɪt")
  
file_path: TTS/tests/text_tests/test_tokenizer.py
imports: import unittest
  from dataclasses import dataclass, field
  from coqpit import Coqpit
  from TTS.tts.utils.text.characters import Graphemes, IPAPhonemes, _blank, _bos, _eos, _pad, _phonemes, _punctuations
  from TTS.tts.utils.text.phonemizers import ESpeak
  from TTS.tts.utils.text.tokenizer import TTSTokenizer
label_desc: Use image node_id 8 for calling the TestTTSTokenizer obj's underlying member method code with example usage: obj.test_not_found_characters() without return types