@Override
 @Test
 public void collectLong() {
   MutableBag<Integer> integers = UnmodifiableBag.of(HashBag.newBagWith(1, 2, 2, 3, 3, 3));
   Assert.assertEquals(
       LongHashBag.newBagWith(1L, 2L, 2L, 3L, 3L, 3L),
       integers.collectLong(PrimitiveFunctions.unboxIntegerToLong()));
 }