enable graph opt at backend test

Author: zhijxu-MS

tests/backend_test_base.py

@@ -18,6 +18,7 @@
 from common import get_test_config
 from tf2onnx import utils
 from tf2onnx.tfonnx import process_tf_graph, tf_optimize
+from tf2onnx.graph import GraphUtil
 
 
 # pylint: disable=missing-docstring,invalid-name,unused-argument,using-constant-test
@@ -140,6 +141,7 @@ def run_test_case(self, feed_dict, input_names_with_port, output_names_with_port
         with tf.Session() as sess:
             g = process_tf_graph(sess.graph, opset=self.config.opset, output_names=output_names_with_port,
                                  target=self.config.target, **process_args)
+            g = GraphUtil.optimize_graph(g)
             actual = self._run_backend(g, output_names_with_port, onnx_feed_dict)
 
         for expected_val, actual_val in zip(expected, actual):

tf2onnx/graph.py

@@ -1138,7 +1138,7 @@ def create_graph_from_onnx_graph(graph_proto, opset_version=None):
             for attr_name, attr_val in n.attr.items():
                 if attr_val.HasField('g'):
                     # it was assumed that the a.g has inferred shapes/dtypes.
-                    sub_g = GraphUtil.create_graph_from_onnx_graph(attr_val.g)
+                    sub_g = GraphUtil.create_graph_from_onnx_graph(attr_val.g, opset_version)
                     n.set_body_graph_as_attr(attr_name, sub_g)
         return g