@Test
  public void factoryTest() {
    IdSigningService idSigningService = new AmbryIdSigningServiceFactory(null, null).getIdSigningService();
    assertEquals("Type does not match expected", AmbryIdSigningService.class, idSigningService.getClass());
  }
Test that {@link AmbryIdSigningServiceFactory} works correctly.
ambry-frontend/src/test/java/com/github/ambry/frontend/AmbryIdSigningServiceTest.java