diff --git a/test/test_onnx.py b/test/test_onnx.py
index 52cbc6defd3..ec3e8f685ab 100644
--- a/test/test_onnx.py
+++ b/test/test_onnx.py
@@ -65,9 +65,9 @@ def to_numpy(tensor):
                 torch.testing.assert_allclose(outputs[i], ort_outs[i], rtol=1e-03, atol=1e-05)
             except AssertionError as error:
                 if tolerate_small_mismatch:
-                    assert ("(0.00%)" in str(error)), str(error)
+                    self.assertIn("(0.00%)", str(error), str(error))
                 else:
-                    assert False, str(error)
+                    raise
 
     def test_nms(self):
         boxes = torch.rand(5, 4)