Iterator<String> iterator = emptyIterator();
    assertThrows(NoSuchElementException.class, () -> getOnlyElement(iterator));
  }

  public void testGetOnlyElement_noDefault_moreThanOneLessThanFiveElements() {
    Iterator<String> iterator = asList("one", "two").iterator();
    IllegalArgumentException expected =
        assertThrows(IllegalArgumentException.class, () -> getOnlyElement(iterator));