message: [tfgan] Add default serving key to unittest
diff: @@ -26,8 +26,11 @@ from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import variable_scope
  from tensorflow.python.platform import test
  +from tensorflow.python.saved_model import signature_constants
  from tensorflow.python.training import training
  +_DEFAULT_SERVING_KEY = signature_constants.DEFAULT_SERVING_SIGNATURE_DEF_KEY
  +
  def dummy_loss(gan_model, add_summaries=True): # pylint:disable=unused-argument
  return math_ops.reduce_sum(gan_model.discriminator_real_outputs -
  @@ -78,7 +81,8 @@ class GANHeadTest(test.TestCase):
  def test_modes_predict(self):
  spec = self._test_modes_helper(model_fn_lib.ModeKeys.PREDICT)
  - self.assertItemsEqual(('predict',), spec.export_outputs.keys())
  + self.assertItemsEqual((_DEFAULT_SERVING_KEY, 'predict'),
  + spec.export_outputs.keys())
  def test_modes_eval(self):
  self._test_modes_helper(model_fn_lib.ModeKeys.EVAL)
  