Seems we need add unit test to make sure onnx work properly.

[pkuyym]

I execute sh setup.sh and all python dependencies are installed successfully. However, I can't run convert.py and the error message is:

Traceback (most recent call last):
  File "convert.py", line 18, in <module>
    from onnx import helper, checker
  File "/usr/local/lib/python2.7/dist-packages/onnx/__init__.py", line 10, in <module>
    import onnx.helper  # noqa
  File "/usr/local/lib/python2.7/dist-packages/onnx/helper.py", line 15, in <module>
    import onnx.defs as defs
  File "/usr/local/lib/python2.7/dist-packages/onnx/defs/__init__.py", line 6, in <module>
    import onnx.onnx_cpp2py_export.defs as C
ImportError: /usr/local/lib/python2.7/dist-packages/onnx/onnx_cpp2py_export.so: undefined symbol: _ZNK6google8protobuf7Message13SpaceUsedLongEv

[kuke]

It should be a known problem in onnx, see:

onnx/onnx#489
onnx/onnx-caffe2#19

[pkuyym]

@kuke Thanks, I suspect that incorrect version of protoc would results in the failure. So we should make the installation for onnx more robust.