    @Test(expected=IllegalArgumentException.class)
    public void throws_exception_if_start_date_after_end_date() {

        LocalDate d1 = LocalDate.of(2016, 1, 10);
        LocalDate d2 = LocalDate.of(2016, 1, 5);
        Arrispwgen.generate_multi(d1, d2, DEFAULT_SEED);
    }