Function rollup_three_cols

nodedb-sql/src/planner/grouping_sets.rs:300–304

()

    #[test]
    fn rollup_three_cols() {
        let gb = parse_group_by("SELECT a, b, c, SUM(x) FROM t GROUP BY ROLLUP (a, b, c)");
        let result = expand_group_by(&gb).unwrap().unwrap();
        assert_eq!(result.grouping_sets.len(), 4); // (a,b,c),(a,b),(a),()
    }
}