blackie

~Test are stuck because of [this](https://github.com/kentcdodds/dom-testing-library/issues/194)~

@juliankrispel Not familiar in test. How about `karma`, `mocha`, `chai`(for BDD Assertion Library), `enzyme`(for React ), `sinon`(for test double) and `Istanbul`(for code coverage)?

Maybe we should add a param for direction into setSelection function, so that we can make sure the caret is at the end position of paragraph, if the user press...

Btw, i add `check` param into each flow script to avoid start a flow server(it may cache errors even if you have fix it)