def test_missing_field_raises_exception(self, constructor, none_field):
    """Tests that aggregator fail if a required field is missing."""
    input_graph = self._get_input_graph([none_field])
    with self.assertRaisesRegexp(ValueError, none_field):
      constructor(tf.unsorted_segment_sum)(input_graph)
Tests that aggregator fail if a required field is missing.
graph_nets/tests/blocks_test.py