@Test
public void testClear() {

  LOG.info("Test clear");
  // use addAll
  set.addAll(list);
  assertEquals(NUM, set.size());
  assertFalse(set.isEmpty());
  // Advance the bookmark.
  Iterator<Integer> bkmrkIt = set.getBookmark();
  for (int i=0; i<set.size()/2+1; i++) {
    bkmrkIt.next();
  }
  assertTrue(bkmrkIt.hasNext());
  // clear the set
  set.clear();
  assertEquals(0, set.size());
  assertTrue(set.isEmpty());
  bkmrkIt = set.getBookmark();
  assertFalse(bkmrkIt.hasNext());
  // poll should return an empty list
  assertEquals(0, set.pollAll().size());
  assertEquals(0, set.pollN(10).size());
  assertNull(set.pollFirst());
  // iterator should be empty
  Iterator<Integer> iter = set.iterator();
  assertFalse(iter.hasNext());
  LOG.info("Test clear - DONE");
}