AttributeError: 'DummyComm' object has no attribute 'messages'

[picca]

Hello, I am preparing the ipywidget 8.1.2 Debian package.

But the tests suite failed like this.

I would like your help in order to understand what is going on.

thanks for considering

Frederic

cd python/ipywidgets ; PYTHONPATH=/<<PKGBUILDDIR>>/debian/python3-ipywidgets/usr/lib/python3.11/dist-packages pytest --cov=ipywidgets ipywidgets # || true
============================= test session starts ==============================
platform linux -- Python 3.11.8, pytest-8.1.1, pluggy-1.4.0
rootdir: /<<PKGBUILDDIR>>/python/ipywidgets
configfile: pyproject.toml
plugins: cov-4.1.0
collected 308 items

ipywidgets/tests/test_embed.py ........                                  [  2%]
ipywidgets/widgets/tests/test_datetime_serializers.py .........          [  5%]
ipywidgets/widgets/tests/test_docutils.py ..                             [  6%]
ipywidgets/widgets/tests/test_interaction.py ........................... [ 14%]
.........                                                                [ 17%]
ipywidgets/widgets/tests/test_link.py ..                                 [ 18%]
ipywidgets/widgets/tests/test_selectioncontainer.py ..................   [ 24%]
ipywidgets/widgets/tests/test_send_state.py FF                           [ 25%]
ipywidgets/widgets/tests/test_set_state.py FFFFFFFFFFFFFFFF..........    [ 33%]
ipywidgets/widgets/tests/test_traits.py ..............................   [ 43%]
ipywidgets/widgets/tests/test_utils.py .....                             [ 44%]
ipywidgets/widgets/tests/test_widget.py .....                            [ 46%]
ipywidgets/widgets/tests/test_widget_box.py ....                         [ 47%]
ipywidgets/widgets/tests/test_widget_button.py .                         [ 48%]
ipywidgets/widgets/tests/test_widget_datetime.py ....................... [ 55%]
....................................................                     [ 72%]
ipywidgets/widgets/tests/test_widget_float.py ...                        [ 73%]
ipywidgets/widgets/tests/test_widget_image.py ................           [ 78%]
ipywidgets/widgets/tests/test_widget_naive_datetime.py ..........        [ 81%]
ipywidgets/widgets/tests/test_widget_output.py ........                  [ 84%]
ipywidgets/widgets/tests/test_widget_selection.py ..........             [ 87%]
ipywidgets/widgets/tests/test_widget_string.py ....                      [ 88%]
ipywidgets/widgets/tests/test_widget_templates.py ................       [ 94%]
ipywidgets/widgets/tests/test_widget_time.py ..........                  [ 97%]
ipywidgets/widgets/tests/test_widget_upload.py ........                  [100%]

=================================== FAILURES ===================================
____________________________ test_empty_send_state _____________________________

    def test_empty_send_state():
        w = SimpleWidget()
        w.send_state([])
>       assert w.comm.messages == []
E       AttributeError: 'DummyComm' object has no attribute 'messages'

ipywidgets/widgets/tests/test_send_state.py:24: AttributeError
_____________________________ test_empty_hold_sync _____________________________

    def test_empty_hold_sync():
        w = SimpleWidget()
        with w.hold_sync():
            pass
>       assert w.comm.messages == []
E       AttributeError: 'DummyComm' object has no attribute 'messages'

ipywidgets/widgets/tests/test_send_state.py:31: AttributeError
_________________________ test_set_state_simple[True] __________________________

echo = True

    def test_set_state_simple(echo):
        w = SimpleWidget()
        w.set_state(dict(
            a=True,
            b=[True, False, True],
            c=[False, True, False],
        ))
    
>       assert len(w.comm.messages) == (1 if echo else 0)
E       AttributeError: 'DummyComm' object has no attribute 'messages'
...

[antonio-rojas]

This is caused by pytest 8. It works fine with 7.

[cjwatson]

This looks like a duplicate of #3883.