@Test public void quinone_subset() throws Exception {

    Graph g = Graph.fromSmiles("oc1ccc(o)cc1");
    // mocks the case where the oxygen atoms are already double bonded - we
    // therefore don't include those of the adjacent carbons in the vertex
    // subset to be matched
    Matching m = Matching.empty(g);
    MaximumMatching.maximise(g, m, 0, IntSet.allOf(2, 3, 6, 7));
    assertThat(m.matches(), hasItems(Tuple.of(2, 3),
                                     Tuple.of(6, 7)));
}