@Test public void simple_augment_subset() throws Exception {

    Graph g = Graph.fromSmiles("cccc");
    Matching m = Matching.empty(g);
    m.match(1, 2);
    // no vertex '3' matching can not be improved
    MaximumMatching.maximise(g, m, 2, IntSet.allOf(0, 1, 2));
    assertThat(m.matches(),
               hasItems(Tuple.of(1, 2)));
}