class_docstr: Tests :class:`~texar.tf.modules.UnidirectionalRNNClassifierTest` class.
      
docstr: Tests the functionality of automatically collecting trainable
  variables.
docstr_tok: ["Tests","the","functionality","of","automatically","collecting","trainable","variables","."]
code: def test_trainable_variables(self):
      """Tests the functionality of automatically collecting trainable
      variables.
      """
      inputs = tf.placeholder(dtype=tf.float32, shape=[None, None, 100])
  
      # case 1
      clas = UnidirectionalRNNClassifier()
      _, _ = clas(inputs)
      self.assertEqual(len(clas.trainable_variables), 2 + 2)
  
      # case 2
      hparams = {
          "output_layer": {"num_layers": 2},
          "logit_layer_kwargs": {"use_bias": False},
      }
      clas = UnidirectionalRNNClassifier(hparams=hparams)
      _, _ = clas(inputs)
      self.assertEqual(len(clas.trainable_variables), 2 + 2 + 2 + 1)
      _, _ = clas(inputs)
      self.assertEqual(len(clas.trainable_variables), 2 + 2 + 2 + 1)
  
imports: import numpy
  import tensorflow
  from texar.tf.modules.classifiers.rnn_classifiers import UnidirectionalRNNClassifier
label_desc: Use image node_id 1 for calling the UnidirectionalRNNClassifierTest obj's underlying member method code with example usage: obj.test_trainable_variables() without return types