Make test test_smollm 20% faster (#2107)

Co-authored-by: Justin Chu <justinchuby@users.noreply.github.com>

Author: xadupre

onnxscript/rewriter/ort_fusions/_test_utils.py

@@ -2,9 +2,6 @@
 # Licensed under the MIT License.
 from __future__ import annotations
 
-import os
-import tempfile
-
 import numpy as np
 import onnx
 import onnxruntime
@@ -27,13 +24,13 @@ def _save(model, modelpath):
 
 def ort_run(model_name: str, model, inputs):
     providers = ["CPUExecutionProvider"]
-    with tempfile.TemporaryDirectory() as temp_dir:
-        model_path = os.path.join(temp_dir, f"{model_name}.onnx")
-        _save(model, model_path)
-        # Run model
-        session = onnxruntime.InferenceSession(model_path, providers=providers)
-        ort_outputs = session.run(None, inputs)
-    return ort_outputs
+    model_proto = ir.serde.serialize_model(model)
+    options = onnxruntime.SessionOptions()
+    options.graph_optimization_level = onnxruntime.GraphOptimizationLevel.ORT_DISABLE_ALL
+    session = onnxruntime.InferenceSession(
+        model_proto.SerializeToString(), options, providers=providers
+    )
+    return session.run(None, inputs)
 
 
 def assert_allclose(outputs, expected_outputs, rtol=1e-2, atol=1e-2):