comm package throws NotImplementedError: Cannot

[pllim]

Example log: https://github.com/spacetelescope/jdaviz/actions/runs/4481154442/jobs/7877457906?pr=2105

All the ipy* package versions:

comm==0.1.2
...
ipydatawidgets==4.3.3
ipygoldenlayout==0.4.0
ipykernel==6.22.0
ipympl==0.9.3
ipypopout==1.0.0
ipysplitpanes==0.2.0
ipython==8.11.0
ipython-genutils==0.2.0
ipyvolume==0.6.1
ipyvue==1.9.0
ipyvuetify==1.8.5
ipywebrtc==0.6.0
ipywidgets==8.0.5

Traceback:

jdaviz/app.py:9: in <module>
    import ipyvue
ipyvue/__init__.py:2: in <module>
    from .Html import Html
ipyvue/Html.py:2: in <module>
    from .VueWidget import VueWidget
ipyvue/VueWidget.py:8: in <module>
    from .ForceLoad import force_load_instance
ipyvue/ForceLoad.py:12: in <module>
    force_load_instance = ForceLoad()
ipywidgets/widgets/widget.py:504: in __init__
    self.open()
ipywidgets/widgets/widget.py:517: in open
    state, buffer_paths, buffers = _remove_buffers(self.get_state())
ipywidgets/widgets/widget.py:615: in get_state
    value = to_json(getattr(self, k), self)
traitlets/traitlets.py:703: in __get__
    return self.get(obj, cls)
traitlets/traitlets.py:659: in get
    default = obj.trait_defaults(self.name)
traitlets/traitlets.py:1872: in trait_defaults
    return self._get_trait_default_generator(names[0])(self)
traitlets/traitlets.py:627: in default
    return self.make_dynamic_default()
ipywidgets/widgets/trait_types.py:365: in make_dynamic_default
    return self.klass(*(self.default_args or ()),
ipywidgets/widgets/widget_layout.py:86: in __init__
    super().__init__(**kwargs)
ipywidgets/widgets/widget.py:504: in __init__
    self.open()
ipywidgets/widgets/widget.py:535: in open
    self.comm = create_comm(**args)
comm/__init__.py:27: in _create_comm
    raise NotImplementedError("Cannot ")
E   NotImplementedError: Cannot

@maartenbreddels , do you know what is going on here? Thanks!

[martinRenou]

We've been discussing exactly this this morning with @maartenbreddels.

The reason you are seing this is because you are not running under an ipykernel session, so ipykernel has not registered its comm implementation.

For now, you may fix it by doing import ipykernel.ipkernel in your test session, which has a byproduct of registering the ipykernel comm implementation.

We will want to improve this situation in the core comm module or/and in ipywidgets.

[pllim]

I put that import in conftest.py but didn't seem to help. Where should I import it for it to work? See spacetelescope/jdaviz#2105

[giswqs]

I just ran into the same error.

[martinRenou]

This should now be fixed using the latest comm package