[pytest integration] (Windows fatal exception: code 0x80010108) @ comtypes

Description

Running pytest with pywinauto causes an exception in shutdown of comtypes. Tests are collected / run correctly, but at the end there’s always an exception output.

This breaks test discovery in VSCode, though I can work around it by moving import statements to the inside of fixtures / functions.

I am not sure if this is an issue with how I am using pytest and pywinauto, or its a bug.

I tried python 3.6 (Visual Studio 2017), 3.7 (Anaconda3), and 3.8 (python.org).

Example code

File test_case.py

import pytest
from pywinauto.application import Application

def test_case():
    assert True

Test discovery

In the directory containing test_case.py python -m pytest --collect-only

Output

========================================================================================= test session starts ========================================================================================== 
platform win32 -- Python 3.8.0, pytest-5.3.1, py-1.8.0, pluggy-0.13.1
rootdir: C:\Users\Yujin\Desktop\pytest_pywinauto
collected 1 item
<Module test_case.py>
  <Function test_case>

=========================================================================================== warnings summary =========================================================================================== 
C:\Users\Yujin\AppData\Roaming\Python\Python38\site-packages\win32\lib\pywintypes.py:2
  C:\Users\Yujin\AppData\Roaming\Python\Python38\site-packages\win32\lib\pywintypes.py:2: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
    import imp, sys, os

-- Docs: https://docs.pytest.org/en/latest/warnings.html
========================================================================================== 1 warning in 0.17s ========================================================================================== 
Windows fatal exception: code 0x80010108

Thread 0x0000625c (most recent call first):
  File "C:\Users\Yujin\AppData\Roaming\Python\Python38\site-packages\comtypes\__init__.py", line 185 in shutdown
Windows fatal exception: code 0x80010108

Thread 0x0000625c (most recent call first):
  File "C:\Users\Yujin\AppData\Roaming\Python\Python38\site-packages\comtypes\__init__.py", line 185 in shutdown

Running the test

python -m pytest

C:\Users\Yujin\Desktop\pytest_pywinauto>"C:/Program Files/Python38/python.exe" -m pytest
========================================================================================= test session starts ========================================================================================== 
platform win32 -- Python 3.8.0, pytest-5.3.1, py-1.8.0, pluggy-0.13.1
rootdir: C:\Users\Yujin\Desktop\pytest_pywinauto
collected 1 item                                                                                                                                                                                         

test_case.py .                                                                                                                                                                                    [100%] 

=========================================================================================== warnings summary =========================================================================================== 
C:\Users\Yujin\AppData\Roaming\Python\Python38\site-packages\win32\lib\pywintypes.py:2
  C:\Users\Yujin\AppData\Roaming\Python\Python38\site-packages\win32\lib\pywintypes.py:2: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
    import imp, sys, os

-- Docs: https://docs.pytest.org/en/latest/warnings.html
===================================================================================== 1 passed, 1 warning in 0.18s ===================================================================================== 
Windows fatal exception: code 0x80010108

Thread 0x00005e8c (most recent call first):
  File "C:\Users\Yujin\AppData\Roaming\Python\Python38\site-packages\comtypes\__init__.py", line 185 in shutdown
Windows fatal exception: code 0x80010108

Thread 0x00005e8c (most recent call first):
  File "C:\Users\Yujin\AppData\Roaming\Python\Python38\site-packages\comtypes\__init__.py", line 185 in shutdown

Specifications

• pywin32 version: 227
• comtypes version: 1.1.7
• Pytest version: 5.3.1
• Pywinauto version: 0.6.8
• Python version and bitness: 3.8 (64 bit) (also tried 3.6, 3.7)
• Platform and OS: Win10 x64

[Fobos23]

I started pytest with -p no:faulthandler and it helped me. Look at this for more information.

[KyleKing]

Ok, so this is the minimum code to reproduce the error:

import comtypes
import comtypes.client

UIA_dll = comtypes.client.GetModule('UIAutomationCore.dll')
ui_automation_client = comtypes.gen.UIAutomationClient
iuia = comtypes.CoCreateInstance(
    ui_automation_client.CUIAutomation().IPersist_GetClassID(),
    interface=ui_automation_client.IUIAutomation,
    clsctx=comtypes.CLSCTX_INPROC_SERVER,
).GetRootElement()


def test_case():
    assert True

This above snippet is modified from the below pywinauto code:

https://github.com/pywinauto/pywinauto/blob/4005bff2aacb6e5421a43abdbdd2f4c178ca53b4/pywinauto/windows/uia_defines.py#L43-L64

I’m a little out of my depth here. From what I can piece together, this only occurs when I call the above snippet (the simplified code from pywinauto–no need to import pywinauto) and use pytest. Calling the snippet with Python doesn’t throw the fatal exception.

I can’t locate what calls the shutdown() method from comtypes that is reporting the Fatal exception on couninitialize. I tried to call the snippet with multiprocess, but I haven’t been able to create an example without pytest

What do you think? What could I try for next steps?