Iterator<List<Integer>> permutations = permutationSet.iterator();

    assertNextPermutation(new ArrayList<>(), permutations);
    assertNoMorePermutations(permutations);
  }

  public void testOrderedPermutationSetOneElement() {
    List<Integer> list = newArrayList(1);
    Iterator<List<Integer>> permutations = Collections2.orderedPermutations(list).iterator();

    assertNextPermutation(newArrayList(1), permutations);