Add unit test.

Author: jmdobry

pubsub/test/topics.test.js

@@ -42,6 +42,7 @@ describe(`pubsub:topics`, () => {
  program.createTopic(topicName, callback);
  program.deleteTopic(topicName, callback);
  program.publishMessage(topicName, {}, callback);
+ program.publishOrderedMessage(topicName, {}, callback);
  program.listTopics(callback);
  program.getTopicPolicy(topicName, callback);
  program.setTopicPolicy(topicName, callback);