public void start() {
    commandTopicBackup.initialize();
    commandConsumer.assign(Collections.singleton(commandTopicPartition));
  }
@Test
  public void shouldAssignCorrectPartitionToConsumer() {
    // When:
    commandTopic.start();

    // Then:
    verify(commandConsumer)
        .assign(eq(Collections.singleton(new TopicPartition(COMMAND_TOPIC_NAME, 0))));
  }