@Test
public void testOneConsumerNoTopic() {

    String consumerId = "consumer";
    Map<String, Integer> partitionsPerTopic = new HashMap<>();
    Map<String, List<TopicPartition>> assignment = assignor.assign(partitionsPerTopic,
            Collections.singletonMap(consumerId, Collections.<String>emptyList()));
    assertEquals(Collections.singleton(consumerId), assignment.keySet());
    assertTrue(assignment.get(consumerId).isEmpty());
}