Investigate exceptions with pytest-qt

[JamesWrigley]

Found a weird bug while running the tests with pytest-qt installed:

(extra_foam) ➜  EXtra-foam git:(pytest) python3 -m pytest extra_foam -k foo -s
============================================================================================================= test session starts =============================================================================================================
platform linux -- Python 3.10.0, pytest-6.2.5, py-1.11.0, pluggy-1.0.0 -- /home/james/.conda/envs/extra_foam/bin/python3
cachedir: .pytest_cache
PyQt5 5.13.2 -- Qt runtime 5.13.2 -- Qt compiled 5.13.2
rootdir: /home/james/git/EXtra-foam, configfile: pytest.ini
plugins: qt-4.0.2
collected 614 items / 613 deselected / 1 selected

extra_foam/gui/image_tool/tests/test_image_tool.py::TestImageTool::testFoo libpng warning: iCCP: known incorrect sRGB profile
Foo
tearDown()
PASSEDtearDownClass()
Exceptions caught in Qt event loop:
________________________________________________________________________________
Traceback (most recent call last):
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 550, in connect
    sock = self._connect()
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 606, in _connect
    raise err
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 594, in _connect
    sock.connect(socket_address)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/james/git/EXtra-foam/extra_foam/gui/ctrl_widgets/data_source_widget.py", line 841, in updateAvailableSources
    ret = self._mon.get_available_sources()
  File "/home/james/git/EXtra-foam/extra_foam/database/mondata.py", line 145, in get_available_sources
    ret = pipe.execute()
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/client.py", line 4006, in execute
    conn = self.connection_pool.get_connection('MULTI',
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 1183, in get_connection
    connection.connect()
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 554, in connect
    raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 111 connecting to 127.0.0.1:6379. Connection refused.
________________________________________________________________________________
Exceptions caught in Qt event loop:
________________________________________________________________________________
Traceback (most recent call last):
  File "/home/james/git/EXtra-foam/extra_foam/gui/image_tool/bulletin_view.py", line 115, in _updateProcessCount
    tid, n_processed, n_dropped, n_processed_pulses = \
TypeError: cannot unpack non-iterable NoneType object
________________________________________________________________________________

extra_foam/gui/image_tool/tests/test_image_tool.py::TestImageTool::testFoo ERROR

=================================================================================================================== ERRORS ====================================================================================================================
_________________________________________________________________________________________________ ERROR at teardown of TestImageTool.testFoo __________________________________________________________________________________________________
TEARDOWN ERROR: Exceptions caught in Qt event loop:
________________________________________________________________________________
Traceback (most recent call last):
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 550, in connect
    sock = self._connect()
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 606, in _connect
    raise err
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 594, in _connect
    sock.connect(socket_address)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/james/git/EXtra-foam/extra_foam/gui/ctrl_widgets/data_source_widget.py", line 841, in updateAvailableSources
    ret = self._mon.get_available_sources()
  File "/home/james/git/EXtra-foam/extra_foam/database/mondata.py", line 145, in get_available_sources
    ret = pipe.execute()
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/client.py", line 4006, in execute
    conn = self.connection_pool.get_connection('MULTI',
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 1183, in get_connection
    connection.connect()
  File "/home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py", line 554, in connect
    raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 111 connecting to 127.0.0.1:6379. Connection refused.
________________________________________________________________________________
Traceback (most recent call last):
  File "/home/james/git/EXtra-foam/extra_foam/gui/image_tool/bulletin_view.py", line 115, in _updateProcessCount
    tid, n_processed, n_dropped, n_processed_pulses = \
TypeError: cannot unpack non-iterable NoneType object
________________________________________________________________________________
============================================================================================================== warnings summary ===============================================================================================================
../../.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py:2
  /home/james/.conda/envs/extra_foam/lib/python3.10/site-packages/redis/connection.py:2: DeprecationWarning: The distutils package is deprecated and slated for removal in Python 3.12. Use setuptools or check PEP 632 for potential alternati
ves
    from distutils.version import StrictVersion

-- Docs: https://docs.pytest.org/en/stable/warnings.html
=========================================================================================================== short test summary info ===========================================================================================================
ERROR extra_foam/gui/image_tool/tests/test_image_tool.py::TestImageTool::testFoo
============================================================================================ 1 passed, 613 deselected, 1 warning, 1 error in 5.79s ============================================================================================

This occurred with a dummy test that does literally nothing, it's just a pass statement. And it only happens with pytest-qt installed. I looked into it briefly, and what I suspect is happening is that there's a timer running that calls a function that calls Redis, and the timer doesn't stop before Redis is shutdown. This specific error is (probably) caused by self._avail_src_timer in DataSourceWidget, but there are similar timers elsewhere like in BulletinView.

It's interesting that this only happens with the pytest-qt plugin, maybe it does some extra introspection for Qt that's missed by pytest?