@Test
public void mapping() throws Exception {

    UllmannState state = createBenzeneToNaphthalene(AtomMatcher.forAny(), BondMatcher.forAny());
    state.m1[0] = 1;
    state.m1[1] = 2;
    assertThat(state.mapping(), is(state.m1));
    assertThat(state.mapping(), is(not(sameInstance(state.m1))));
}