Karma is deprecated we should move on

[fcollonval]

Problem

Karma is deprecated

Proposed Solution

We should use more modern test tool; Jest is probably the best candidate to avoid yet another tool compared with JupyterLab.

[krassowski]

+1 to jest for simplicity

[fcollonval]

Note: in jupyterlab-git we switched to the testing-library. I think it will be a good candidate for lumino widgets tests.

[krassowski]

What is the selling point over jest?

[fcollonval]

You still need jest as a test runner. The goal of the testing-library is to render components (of any framework) and interact with the DOM to carry out the user actions and introspect it for expectations.

Basically this is what is needed to replace karma while jest is to replace chai and mocha.