message: add test for UnderlineNav > UnderlineNavLink
diff: import React from 'react'
  import PropTypes from 'prop-types'
  import UnderlineNav, {ITEM_CLASS, SELECTED_CLASS} from '../UnderlineNav'
  +import UnderlineNavLink from '../UnderlineNavLink'
  import {mount, render, renderClasses} from '../utils/testing'
  const rendersClass = (node, klass) => renderClasses(node).includes(klass)
  @@ -101,4 +102,22 @@ describe('Caret', () => {
  )
  expect(wrapper.find('span').props().className).toEqual(ITEM_CLASS)
  })
  +
  + it('lets <UnderlineNavLink> do its thing', () => {
  + expect(
  + render(
  + <UnderlineNav>
  + <UnderlineNavLink href="#foo">Foo</UnderlineNavLink>
  + </UnderlineNav>
  + )
  + ).toEqual(
  + render(
  + <UnderlineNav>
  + <a href="#foo" className={ITEM_CLASS}>
  + Foo
  + </a>
  + </UnderlineNav>
  + )
  + )
  + })
  })
  