JupyterLite kernel test

[martinRenou]

For testing kernels on the back-end we have the jupyter-kernel-test tool which is quite convenient, I was thinking (with the number of xeus kernels coming to JupyterLite) it would be nice to have something similar for jupyterlite kernels.

It could probably be using galata or just playwright. It could also be a jest testing tool.

I am opening an issue here to gather ideas on this.

[bollwyvl]

I think testing/spec validation might be something where, in the spirit of #41, we would perhaps benefit from using exactly jupyter-kernel-test, such that spec changes only have to be reflected/improved in one place.

Some thoughts on how we could do this:

• run it in-browser in a browser python kernel, excite the tests with a repl app run by a js test framework
  • would need some more shims (tornado, pyzmq)
  • run the tests as notebooks, etc.
• write a "reverse" kernelmanager
  • launch a small http server (or "real" jupyter_server extension) that can serve jupyterlite,
  • launch a browser to a testing app that has the browser kernels installed
  • i think it's pretty important, architecturally, this is possible to be executed by real browsers, as we have seen that we have sensitivity to this...
    • so if one of the node runners works, it might still need a webdriver-based option
  • have a (browser) serverlite extension that opens a websocket that proxies requests
  • offer a custom jupyter_kernel_test.KernelTests

Either way, and even if we started it here, i imagine we would still end up a separate installable package, and repo in this org, which each kernel's test suite could depend on.