@Test
public void testGetTopicsReturnsImmutable() {

    final List<TopicListing> topicListingList = new ArrayList<>();
    topicListingList.add(new TopicListing("D", false));
    topicListingList.add(new TopicListing("E", false));
    topicListingList.add(new TopicListing("F", false));
    // Create instance
    final TopicList topicList = new TopicList(topicListingList);
    final List<TopicListing> results = topicList.getTopics();
    // Should be immutable.
    expectedException.expect(UnsupportedOperationException.class);
    results.remove(1);
}