message: Update callbacks_test.py
  Add a test case to check the value of `callback.params['samples']` after `model.evaluate()`
diff: @@ -1378,6 +1378,15 @@ class KerasCallbacksTest(keras_parameterized.TestCase):
  callbacks=cbks,
  epochs=1)
  + def test_callback_params_samples(self):
  + x, y = np.ones((64, 3)), np.ones((64, 2))
  + model = testing_utils.get_small_sequential_mlp(
  + num_hidden=10, num_classes=2, input_dim=3)
  + model.compile('sgd', 'mse')
  + callback = keras.callbacks.Callback()
  + model.evaluate(x, y, callbacks=[callback])
  + self.assertEqual(callback.params['samples'], 64)
  +
  # A summary that was emitted during a test. Fields:
  # logdir: str. The logdir of the FileWriter to which the summary was
  