message: add ButtonPrimary test
diff: import React from 'react'
  -import Button from '../Button'
  -import ButtonDanger from '../ButtonDanger'
  -import ButtonLink from '../ButtonLink'
  -import ButtonOutline from '../ButtonOutline'
  +import {Button, ButtonPrimary, ButtonDanger, ButtonLink, ButtonOutline} from '..'
  import {render} from '../utils/testing'
  function noop() {}
  @@ -62,6 +59,12 @@ describe('Button', () => {
  })
  })
  +describe('ButtonPrimary', () => {
  + it('renders a <button>', () => {
  + expect(render(<ButtonPrimary />)).toEqual(render(<button className="btn btn-primary" type="button" />))
  + })
  +})
  +
  describe('ButtonDanger', () => {
  it('renders a <button>', () => {
  expect(render(<ButtonDanger />)).toEqual(render(<button className="btn btn-danger" type="button" />))
  