Basic UI rendering tests

[jacogr]

• Start of Add very basic smoketests for all UI components #2289 (structure & initial basic tests)
• Setup the structure for Webpack/Babel (alias)
• Basic tests starting with components in ui/*
• 1 issue found & fixed (TxList store pending ordering)

[derhuerst]

While I think this is an important thing we need, the tests are, I'd say, almost trivial. I'd rather test if e.g. the component contains the tx hash as text and leave the tests "renders successfully" out.

[ngotchac]

I kind of agree with @derhuerst : a few basic tests to see how it works is fine, but we should have more useful ones. Good first step anyway ! 👍

[jacogr]

The whole idea behind the issue (as logged) is to bring in basic smoketests, i.e. the component renders, no magic. (As per the discussion around Sep in js-dev around the issue - https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#writing-tests - the gist is if you do nothing, at least do the "it renders" test)

From there it needs to be built up - since we have nothing, I would start with where we have bugs, replicate via test, fix it and let it grow organically. (Just pulled in a variety to not just do the simplest, but rather also cases where tied to Redux stores, bringing in context, etc.)

The most valuable place to spend time on test however would be (initially) on the MobX stores where most of the logic resides. (Also the only place where I found an issue thus far)