class_docstr: A collection of decoder tests. This class should be inherited together with
  `tf.test.TestCase`.
class_docstr_tok: ["A","collection","of","decoder","tests",".","This","class","should","be","inherited","together","with","`","tf.test.TestCase","`","."]
docstr: Creates the decoder module.
  
  This must be implemented by child classes and instantiate the appropriate
  decoder to be tested.
docstr_tok: ["Creates","the","decoder","module",".","This","must","be","implemented","by","child","classes","and","instantiate","the","appropriate","decoder","to","be","tested","."]
code: def create_decoder(self, helper, mode):
      """Creates the decoder module.
  
      This must be implemented by child classes and instantiate the appropriate
      decoder to be tested.
      """
      raise NotImplementedError
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import tensorflow
  import numpy
  from seq2seq.decoders import BasicDecoder, AttentionDecoder, AttentionLayerDot
  from seq2seq.decoders import beam_search_decoder
  from seq2seq.inference import beam_search
  from seq2seq.contrib.seq2seq import helper
label_desc: Use image node_id 2 for calling the DecoderTests obj's underlying member method code with example usage: obj.create_decoder(helper, mode) without return types