@Test
public void testNextN() throws Exception {

    UllmannState state = createBenzeneToNaphthalene(AtomMatcher.forAny(), BondMatcher.forAny());
    assertThat(state.nextN(0), is(0));
    state.size = 1;
    assertThat(state.nextN(0), is(1));
    state.size = 2;
    assertThat(state.nextN(0), is(2));
}