[FIX] owboxplot: Fix an error in widget cleanup during tests

[ales-erjavec]

Issue

Since biolab/orange-widget-base#204 was released, Orange.widgets.tests.test_workflows fails with

Traceback (most recent call last):
  File "/home/runner/work/orange3/orange3/.tox/pyqt6/lib/python3.9/site-packages/Orange/widgets/visualize/owboxplot.py", line 257, in eventFilter
    if obj is self.box_view.viewport() and \
AttributeError: 'OWBoxPlot' object has no attribute 'box_view'
ERROR: InvocationError for command /home/runner/work/orange3/orange3/.tox/pyqt6/bin/python -m unittest Orange.widgets.tests (exited with code -6 (SIGABRT)) (exited with code -6)

Description of changes

Change order of conditions in eventFilter to short-circuit access to widget members which can no longer exist (empty self.__dict__).

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #6136 (ee44ae0) into master (79e4237) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6136   +/-   ##
=======================================
  Coverage   86.48%   86.48%           
=======================================
  Files         315      315           
  Lines       67771    67771           
=======================================
+ Hits        58610    58611    +1     
+ Misses       9161     9160    -1     

[janezd]

This looks bad. Do I understand correctly that some methods can be invoked when the widget is being destroyed and already has an empty __dict__?

Are there any other methods (that we use) in which we need to be careful?

Is this limited to tests (which have no screen) or can it also happen to the user?

[PrimozGodec]

Tests are failing due to changes in pandas. I propose a temporary solution since I think it is a bug in pandas #6145

[ales-erjavec]

Do I understand correctly that some methods can be invoked when the widget is being destroyed and already has an empty __dict__?

Yes.

Are there any other methods (that we use) in which we need to be careful?

event(), but other virtual event handlers could have the same problem.

Is this limited to tests (which have no screen) or can it also happen to the user?

I guess it can happen to the user also.

[markotoplak]

I am fixing the oldest deps tests in a separate PR - no need to worry about that.