class_docstr: Tests variable utterance text data class.
      
code: def setUp(self):
      tf.test.TestCase.setUp(self)
  
      # Create test data
      vocab_list = [
          "word",
          "sentence",
          "词",
          "response",
          "dialog",
          "1",
          "2",
      ]
      vocab_file = tempfile.NamedTemporaryFile()
      vocab_file.write("\n".join(vocab_list).encode("utf-8"))
      vocab_file.flush()
      self._vocab_file = vocab_file
      self._vocab_size = len(vocab_list)
  
      text = [
          "This is a dialog 1 sentence . ||| This is a dialog 1 sentence . "
          "||| This is yet another dialog 1 sentence .",  # //
          "This is a dialog 2 sentence . ||| "
          "This is also a dialog 2 sentence . ",  # //
          "词 词 词 ||| word",  # //
          "This This",  # //
          "1 1 1 ||| 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ||| 1 1 1 ||| 2",
      ]
      text_file = tempfile.NamedTemporaryFile()
      text_file.write("\n".join(text).encode("utf-8"))
      text_file.flush()
      self._text_file = text_file
  
      self._hparams = {
          "num_epochs": 50,
          "batch_size": 3,
          "shuffle": False,
          "dataset": {
              "files": self._text_file.name,
              "vocab_file": self._vocab_file.name,
              "variable_utterance": True,
              "max_utterance_cnt": 3,
              "max_seq_length": 10,
          },
      }
  
imports: import tempfile
  import copy
  import numpy
  import tensorflow
  import texar.tf
label_desc: Use image node_id 1 for calling the VarUttMonoTextDataTest obj's underlying member method code with example usage: obj.setUp() without return types