set up unit-testing tools

[py-in-the-sky]

Also write a few unit tests to get things started.

[py-in-the-sky]

@mbrookes If I got things set up right, you should be able to checkout this branch and run npm install && npm test without any errors. I just wanted to get some tools set up for testing. I figure we can fill out the test suite over time. The formsy-react repo has many great tests that we can model ours after.

[mbrookes]

Thanks for this. 👍

I just upgraded babel. Could you rebase please?

[mbrookes]

Also, some interesting discussion here. We're never going to have performance problems with this small set of components, but just for reference: mui/material-ui#3241 (comment)

[py-in-the-sky]

I rebased. The latest uses Karma, which both material-ui and formsy-react use. There are some things that just can't be tested outside an actual browser right now.

Regarding shallow rendering, I haven't looked into this enough to fully understand why, but tests involving formsy don't work without full rendering. The React docs provide only a short review of some limitations of shallow rendering.

[mbrookes]

Love it!

Thank you for getting this up and running!!!