docstr: Test char to ID and ID to char conversion
docstr_tok: ["Test","char","to","ID","and","ID","to","char","conversion"]
code: def test_char_lookup(self):
      """Test char to ID and ID to char conversion"""
      self.characters_empty.characters = "abc"
      self.characters_empty.punctuations = ".,;:!? "
      self.characters_empty.pad = "[PAD]"
      self.characters_empty.eos = "[EOS]"
      self.characters_empty.bos = "[BOS]"
      self.characters_empty.blank = "[BLANK]"
  
      # char to ID
      self.assertEqual(self.characters_empty.char_to_id("[PAD]"), 0)
      self.assertEqual(self.characters_empty.char_to_id("[EOS]"), 1)
      self.assertEqual(self.characters_empty.char_to_id("[BOS]"), 2)
      self.assertEqual(self.characters_empty.char_to_id("[BLANK]"), 3)
      self.assertEqual(self.characters_empty.char_to_id("a"), 4)
      self.assertEqual(self.characters_empty.char_to_id("b"), 5)
      self.assertEqual(self.characters_empty.char_to_id("c"), 6)
      self.assertEqual(self.characters_empty.char_to_id("."), 7)
      self.assertEqual(self.characters_empty.char_to_id(","), 8)
      self.assertEqual(self.characters_empty.char_to_id(";"), 9)
      self.assertEqual(self.characters_empty.char_to_id(":"), 10)
      self.assertEqual(self.characters_empty.char_to_id("!"), 11)
      self.assertEqual(self.characters_empty.char_to_id("?"), 12)
      self.assertEqual(self.characters_empty.char_to_id(" "), 13)
  
      # ID to char
      self.assertEqual(self.characters_empty.id_to_char(0), "[PAD]")
      self.assertEqual(self.characters_empty.id_to_char(1), "[EOS]")
      self.assertEqual(self.characters_empty.id_to_char(2), "[BOS]")
      self.assertEqual(self.characters_empty.id_to_char(3), "[BLANK]")
      self.assertEqual(self.characters_empty.id_to_char(4), "a")
      self.assertEqual(self.characters_empty.id_to_char(5), "b")
      self.assertEqual(self.characters_empty.id_to_char(6), "c")
      self.assertEqual(self.characters_empty.id_to_char(7), ".")
      self.assertEqual(self.characters_empty.id_to_char(8), ",")
      self.assertEqual(self.characters_empty.id_to_char(9), ";")
      self.assertEqual(self.characters_empty.id_to_char(10), ":")
      self.assertEqual(self.characters_empty.id_to_char(11), "!")
      self.assertEqual(self.characters_empty.id_to_char(12), "?")
      self.assertEqual(self.characters_empty.id_to_char(13), " ")
  
file_path: TTS/tests/text_tests/test_characters.py
imports: import unittest
  from TTS.tts.utils.text.characters import BaseCharacters, BaseVocabulary, Graphemes, IPAPhonemes
label_desc: Use image node_id 6 for calling the BaseCharacterTest obj's underlying member method code with example usage: obj.test_char_lookup() without return types