assertNextPermutation(newArrayList(2, 1, 4, 3), permutations);
    assertNextPermutation(newArrayList(2, 1, 3, 4), permutations);
    assertNoMorePermutations(permutations);
  }

  public void testPermutationSetSize() {
    assertPermutationsCount(1, Collections2.permutations(Collections.<Integer>emptyList()));
    assertPermutationsCount(1, Collections2.permutations(newArrayList(1)));