@Override
      protected Iterator<Set<Integer>> newTargetIterator() {
        return powerSet.iterator();
      }
    }.test();
  }

  public void testPowerSetSize() {
    assertPowerSetSize(1);
    assertPowerSetSize(2, 'a');
    assertPowerSetSize(4, 'a', 'b');
    assertPowerSetSize(8, 'a', 'b', 'c');
    assertPowerSetSize(16, 'a', 'b', 'd', 'e');