@Test
  public void testUnbound() throws IOException {
    CollectorRegistry registry = new CollectorRegistry();
    try {
      HTTPServer s = new HTTPServer(HttpServer.create(), registry, true);
      s.stop();
      fail("Should refuse to use an unbound HttpServer");
    } catch (IllegalArgumentException expected) {
    }
  }

  @Test(expected = IllegalArgumentException.class)
  public void testRefuseUsingUnbound() throws IOException {
    CollectorRegistry registry = new CollectorRegistry();
    HTTPServer s = new HTTPServer(HttpServer.create(), registry, true);
    s.stop();
  }