Echo JS 0.11.0

I don't think it's particularly hard... the issue is, it depends on what you expect from front end testing.

One of the best things about React + Redux, is if done properly, you can cover a *LOT* with unit tests alone on your action creators (dispatch) and the reducer(s).

On the latest project I'm working with... all components are functional and using hooks.  All event handlers for components are using bound action methods from the action creators.

This means, all actions can be tested via call/injection alone... the API and getState/dispatch passed into the event handlers.

All state changes through reducer tests... in the end, the components are pretty straight forward (material-ui) and reliable.  That part is more of a pain to actually test, but less impactful on logical workflows.