verify(listenerContainer).addMessageListener(any(MessageListener.class), collectionCaptor.capture());
Collection<ChannelTopic> topics = collectionCaptor.getValue();
Iterator<ChannelTopic> topicIterator = topics.iterator();
Topic firstTopic = topicIterator.next();
Topic twoTopic = topicIterator.next();
assertEquals("one", firstTopic.getTopic());
assertEquals("two", twoTopic.getTopic());
}