@Test
public void fixTopicShouldChangeAndUpdateAndNotifyNewTopicIfTopicIsNotSet() throws CommandException {

    assertFalse(topic.hasTopic());
    parser.fixTopic(" new topic"); // Includes whitespace from "/topic new topic"
    verify(controller).changeTopic("new topic");
    verify(messageController).showSystemMessage("You changed the topic to: new topic");
    verify(userInterface).showTopic();
}