add tests via nbval

[ianhi]

Describe the issue

It would be great to have a test notebook that was run using nbval and tested against several version of matplotlib as well matplotlib master maybe? This could help pick up errors like #252 more quickly.

[martinRenou]

I agree. We might not even need nbval, a simpler test set with pytest might be enough?

[ianhi]

Do methods such as display get properly tested by pytest?

[ianhi]

Also, if we use jupyterlab-browsercheck maybe we could notice the javascript errors that come from a broken install? I think we added that to ipycytoscape

[martinRenou]

I think we added that to ipycytoscape

Oh did you? I am really interested in this!

[ianhi]

I'm not entirely sure that I added it correctly or that it would pick up every pathology. See dicussion about adding it here: cytoscape/ipycytoscape#131 (added both browser check and build in the PR)

[ianhi]

If the browser check could be made to run a few cells of a notebook then it would be awesome.