Function groups_empty_groups

datafusion/functions-aggregate/src/string_agg.rs:912–930

()

    #[test]
    fn groups_empty_groups() -> Result<()> {
        let mut acc = make_groups_acc(",");

        // 4 groups total, but only groups 0 and 2 receive values
        let values: ArrayRef = Arc::new(LargeStringArray::from(vec!["a", "b"]));
        acc.update_batch(&[values], &[0, 2], None, 4)?;

        let result = evaluate_groups(&mut acc, EmitTo::All);
        assert_eq!(
            result,
            vec![
                Some("a".to_string()),
                None, // group 1: never received a value
                Some("b".to_string()),
                None, // group 3: never received a value
            ]
        );
        Ok(())
    }

    #[test]
    fn groups_multiple_batches() -> Result<()> {