message: get full UnderlineNav test coverage
diff: @@ -51,6 +51,28 @@ describe('Caret', () => {
  expect(wrapper.find('a').props().className).toEqual(ITEM_CLASS)
  })
  + it('adds the SELECTED_CLASS to all children with selected={true}', () => {
  + const wrapper = mount(
  + <UnderlineNav>
  + <a href="#foo" selected>
  + hi
  + </a>
  + </UnderlineNav>
  + )
  + expect(wrapper.find('a').props().className).toEqual(`${ITEM_CLASS} ${SELECTED_CLASS}`)
  + })
  +
  + it('does not duplicate the SELECTED_CLASS on elements that have it', () => {
  + const wrapper = mount(
  + <UnderlineNav>
  + <a href="#foo" className="selected" selected>
  + hi
  + </a>
  + </UnderlineNav>
  + )
  + expect(wrapper.find('a').props().className).toEqual(`${ITEM_CLASS} ${SELECTED_CLASS}`)
  + })
  +
  it('adds activeClassName={SELECTED_CLASS} to anything that looks like a react-router NavLink', () => {
  function NavLink({activeClassName, ...rest}) {
  return <button data-active-class={activeClassName} {...rest} />
  