Function mixed_empty_and_conflicting

datafusion/expr/src/expr.rs:4336–4343

()

        #[test]
        fn mixed_empty_and_conflicting() {
            let m1 = HashMap::from([("key".into(), "a".into())]);
            let m2 = HashMap::new();
            let m3 = HashMap::from([("key".into(), "b".into())]);
            let result = intersect_metadata_for_union([&m1, &m2, &m3]);
            // m2 is skipped; m1 and m3 conflict → dropped
            assert!(result.is_empty());
        }

        #[test]
        fn no_inputs() {