ArrayDequeInbox implements Inbox { @Override public Object poll() { Object result = queue.poll(); progTracker.madeProgress(result != null); return result; } ArrayDequeInbox(ProgressTracker progTracker); @Override boolean isEmpty(); @Nonnull @Override Iterator<Object> iterator(); @Override Object peek(); @Override Object poll(); @Override void remove(); @Override void clear(); Deque<Object> queue(); @Override int size();  }
@Test public void when_pollNonEmpty_then_getItem() { assertEquals(ITEMS.get(0), inbox.poll()); }