Function evaluate_groups

datafusion/functions-aggregate/src/string_agg.rs:797–804

Helper: evaluate and downcast to LargeStringArray

(
        acc: &mut StringAggGroupsAccumulator,
        emit_to: EmitTo,
    )

    /// Helper: evaluate and downcast to LargeStringArray
    fn evaluate_groups(
        acc: &mut StringAggGroupsAccumulator,
        emit_to: EmitTo,
    ) -> Vec<Option<String>> {
        let result = acc.evaluate(emit_to).unwrap();
        let arr = result.as_any().downcast_ref::<LargeStringArray>().unwrap();
        arr.iter().map(|v| v.map(|s| s.to_string())).collect()
    }

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