@Override
        public Result search(Query query, Execution exec) {
            GroupingListHit hit = hits.poll();
            for (Grouping grp : hit.getGroupingList()) {
                grp.setFirstLevel(pass);
                grp.setLastLevel(pass);
            }
            ++pass;
            Result res = exec.search(query);
            res.hits().add(hit);
            return res;
        }
Tests the internal rewriting of rank properties which happens in the query.prepare() call
(triggered by the exc.search call in the below).
container-search/src/test/java/com/yahoo/search/grouping/vespa/GroupingExecutorTestCase.java