message: added missing sparse test
diff: @@ -196,6 +196,7 @@ class BackendUtilsTest(test.TestCase):
  x = keras.Input(shape=(None,), ragged=True)
  self.assertEqual(keras.backend.is_keras_tensor(x), True)
  x = keras.Input(shape=(None, None), sparse=True)
  + self.assertEqual(keras.backend.is_keras_tensor(x), True)
  with self.assertRaises(ValueError):
  keras.backend.is_keras_tensor(0)
  