@Test
public void testUsers() {

    Collection<ByteBuffer> added = addMoreUsers(
            Sets.newHashSet(ByteBuffers.fromString("admin")), service);
    Set<String> existing = added.stream()
            .map(bytes -> ByteBuffers.getString(bytes))
            .collect(Collectors.toSet());
    Assert.assertEquals(existing,
            service.users().stream()
                    .map(bytes -> ByteBuffers.getString(bytes))
                    .collect(Collectors.toSet()));
}