class_docstr: Basic tests on the built-in parlai Dictionary.
class_docstr_tok: ["Basic","tests","on","the","built-in","parlai","Dictionary","."]
code: def test_gpt2_bpe_tokenize(self):
      datapath = ParlaiParser().parse_args([], print_args=False)[
          "datapath"
      ]
      opt = Opt({"dict_tokenizer": "gpt2", "datapath": datapath})
      agent = DictionaryAgent(opt)
      self.assertEqual(
          # grinning face emoji
          agent.gpt2_tokenize("Hello, ParlAI! \U0001f600"),
          GPT2_BPE_RESULT,
      )
      self.assertEqual(
          agent.vec2txt(agent.tok2ind[w] for w in GPT2_BPE_RESULT),
          # grinning face emoji
          "Hello, ParlAI! \U0001f600",
      )
  
imports: from parlai.core.build_data import modelzoo_path
  from parlai.core.dict import find_ngrams
  from parlai.core.params import ParlaiParser
  from parlai.core.dict import DictionaryAgent, TokenizationMode
  from parlai.core.opt import Opt
  import parlai.scripts.build_dict
  from parlai.utils.io import PathManager
  import parlai.utils.testing
  import os
  import shutil
  import unittest
  import pytest
label_desc: Use image node_id 1 for calling the TestDictionary obj's underlying member method code with example usage: obj.test_gpt2_bpe_tokenize() without return types