Widget calls requiring browser context hang during testing

[alex-treebeard]

Describe the bug
The ITKWidgets project cannot test a notebooks that calls a widget which is only initialised when a browser is present

To Reproduce
See InsightSoftwareConsortium/itkwidgets#587

Expected behavior
Can call the initialised widget API successfully

Additional context
This issue occurs because nbclient is an alternative to running a full jupyter web app + server (architecture diagram) and doesn't run a browser context.

Problem cell example

image = itk.image_from_array(array)
print('Dimension', image.GetImageDimension())
print('Components', image.GetNumberOfComponentsPerPixel())

from ipynb.

• Widget docs

[alex-treebeard]

This repo has a pretty advanced setup using Selenium's python APIs @thewtex you can see that they actually test the widget's functionality (not just load it).

[thewtex]

@alex-treebeard here is a high level architecture that aims to:

1. Provide the needed JavaScript, WebGL context
2. Be simple, requiring relatively little code
3. Work with the existing nbmake code

References:

• pytest-pyodide (Selenium pytest browser testing)
• jupyter_server websocket protocols
• jupyter_server extensions

[alex-treebeard]

weights and biases have come up with an interesting cypress-based solution

https://github.com/wandb/weave/blob/4891c2f5d35bb9077d4add9ab4d92536dbf7b00c/integration_test/cypress/e2e/notebooks/notebooks.ts

[thewtex]

Interesting! It does not look like they are running the notebooks in an actual browser, though, from what I can tell.