@Test
public void getUsersById() throws Exception {

    server.enqueue(new MockResponse().setBody("{\n"
          + "  \"users\": [\n"
          + "    \n"
          + userJson + ", "
          + userJson
          + "  ]\n"
          + '}'));
    List<String> ids = new ArrayList<>();
    ids.add("some_id");
    ids.add("another_id");
    Response<List<XingUser>, HttpError> response = resource.getUsersById(ids).execute();
    // If no exception was thrown then the spec is build correctly.
    assertThat(response.body().size()).isEqualTo(2);
}