@Test public void testIteration() { ConcurrentLongHashSet set = new ConcurrentLongHashSet(); assertEquals(set.items(), Collections.emptySet()); set.add(0L); assertEquals(set.items(), new HashSet<>(Arrays.asList(0L))); set.remove(0L); assertEquals(set.items(), Collections.emptySet()); set.add(0L); set.add(1L); set.add(2L); List<Long> values = new ArrayList<>(set.items()); Collections.sort(values); assertEquals(values, Arrays.asList(0L, 1L, 2L)); set.clear(); assertTrue(set.isEmpty()); }