@Test
    void testSinglePassGroupingIsNotForcedWithSingleNodeGroups() {
        MockDispatcher dispatcher = MockDispatcher.create(List.of(new Node(CLUSTER, 0, "host0", 0), new Node(CLUSTER, 2, "host1", 0)));

        IndexedBackend fastSearcher = new IndexedBackend(CLUSTER_PARAMS, dispatcher);
        Query q = new Query("?query=foo");
        GroupingRequest request1 = GroupingRequest.newInstance(q);
        request1.setRootOperation(new AllOperation());

        GroupingRequest request2 = GroupingRequest.newInstance(q);
        AllOperation all = new AllOperation();
        all.addChild(new EachOperation());
        all.addChild(new EachOperation());
        request2.setRootOperation(all);

        assertForceSinglePassIs(false, q);
        fastSearcher.search(SCHEMA, q);
        assertForceSinglePassIs(false, q);
    }
Tests the Fast searcher

@author bratseth
container-search/src/test/java/com/yahoo/prelude/fastsearch/IndexedBackendTestCase.java