### Question:
TrackerIdFetcher { public void setNextProvider(TrackerIdFetcher next) { this.nextTrackerIdFetcher = next; }  void setNextProvider(TrackerIdFetcher next); String get(Http.Context ctx);  }### Answer:
@Test public void should_set_the_next_provider() { doCallRealMethod().when(trackerIdFetcher).setNextProvider(nextTrackerIdFetcher); trackerIdFetcher.setNextProvider(nextTrackerIdFetcher); Assert.assertEquals(Whitebox.getInternalState(trackerIdFetcher, "nextTrackerIdFetcher"), nextTrackerIdFetcher); }