Publishers extends Helper { public Publisher add(String campaignId) { Publisher pub = new Publisher(tracker).setCampaignId(campaignId); tracker.getBusinessObjects().put(pub.getId(), pub); return pub; } Publishers(Tracker tracker); Publisher add(String campaignId); void sendImpressions();  }
@Test public void addTest() { publishers.add("pub"); assertEquals(1, tracker.getBusinessObjects().size()); }