Test with napari rc fails with segmentation fault during process qt viewer buttons events.

🐛 Bug

My test of pre-release on macos fails with segmentation fail after processing some napari button events. In the past such problem was caused by keeping references to Qt objects in some global state. Error is not deterministic and it my happen that after restart test pass.

To Reproduce

https://github.com/4DNucleome/PartSeg/runs/5384644974?check_suite_focus=true

  Current thread 0x00000001116addc0 (most recent call first):
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/napari/utils/events/event.py", line 354 in callback_refs
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/napari/utils/events/event.py", line 432 in connect
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/napari/utils/action_manager.py", line 209 in bind_button
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/napari/_qt/widgets/qt_viewer_buttons.py", line 468 in __init__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/napari/_qt/widgets/qt_viewer_buttons.py", line 432 in _func
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/napari/_qt/widgets/qt_viewer_buttons.py", line 129 in __init__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/napari/_qt/qt_viewer.py", line 208 in __init__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/PartSeg/common_gui/napari_image_view.py", line 911 in __init__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/PartSeg/common_gui/napari_image_view.py", line 160 in __init__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/PartSeg/_roi_mask/image_view.py", line 13 in __init__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/PartSeg/_roi_mask/main_window.py", line 878 in __init__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/PartSeg/_launcher/main_window.py", line 133 in launch
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pytestqt/qt_compat.py", line 156 in exec
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pytestqt/wait_signal.py", line 51 in wait
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pytestqt/wait_signal.py", line 151 in __exit__
    File "/Users/runner/work/PartSeg/PartSeg/package/tests/test_PartSeg/test_main_windows.py", line 62 in test_open_mask
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/python.py", line 192 in pytest_pyfunc_call
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_callers.py", line 39 in _multicall
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_manager.py", line 80 in _hookexec
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_hooks.py", line 265 in __call__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/python.py", line 1718 in runtest
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/runner.py", line 168 in pytest_runtest_call
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_callers.py", line 39 in _multicall
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_manager.py", line 80 in _hookexec
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_hooks.py", line 265 in __call__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/runner.py", line 261 in <lambda>
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/runner.py", line 340 in from_call
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/runner.py", line 260 in call_runtest_hook
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/runner.py", line 221 in call_and_report
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/runner.py", line 132 in runtestprotocol
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/runner.py", line 113 in pytest_runtest_protocol
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_callers.py", line 39 in _multicall
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_manager.py", line 80 in _hookexec
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_hooks.py", line 265 in __call__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/main.py", line 347 in pytest_runtestloop
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_callers.py", line 39 in _multicall
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_manager.py", line 80 in _hookexec
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_hooks.py", line 265 in __call__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/main.py", line 322 in _main
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/main.py", line 268 in wrap_session
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/main.py", line 315 in pytest_cmdline_main
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_callers.py", line 39 in _multicall
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_manager.py", line 80 in _hookexec
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pluggy/_hooks.py", line 265 in __call__
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/config/__init__.py", line 165 in main
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/_pytest/config/__init__.py", line 188 in console_main
    File "/tmp/tox/py38-PyQt5-all/lib/python3.8/site-packages/pytest/__main__.py", line 5 in <module>
    File "/Users/runner/hostedtoolcache/Python/3.8.12/x64/lib/python3.8/runpy.py", line 87 in _run_code
    File "/Users/runner/hostedtoolcache/Python/3.8.12/x64/lib/python3.8/runpy.py", line 194 in _run_module_as_main

Expected behavior

There should be no global reference to old instances.

Environment

napari==0.4.15rc0

Additional context

[Czaki]

I could not reproduce it now. I will try more when I come back to home.

[Czaki]

All test green.