message: fix broken UnderlineNavItem test
diff: @@ -8,8 +8,7 @@ describe('Caret', () => {
  })
  it('renders the given tag prop', () => {
  - const Type = jest.fn()
  - render(<UnderlineNavItem tag={Type} />)
  - expect(Type.mock.calls.length).toBe(1)
  + const Type = props => <div />
  + expect(render(<UnderlineNavItem tag={Type} />)).toEqual(render(<div />))
  })
  })
  