#[test]
    fn test_filter_with_projection_remaps_post_phase_parent_filters() -> Result<()> {
        // Test that FilterExec with a projection must remap parent dynamic
        // filter column indices from its output schema to the input schema
        // before passing them to the child.
        let input_schema = Arc::new(Schema::new(vec![
            Field::new("a", DataType::Int32, false),
            Field::new("b", DataType::Utf8, false),
            Field::new("c", DataType::Float64, false),
        ]));
        let input = Arc::new(EmptyExec::new(Arc::clone(&input_schema)));

        // FilterExec: a > 0, projection=[c@2]
        let predicate = Arc::new(BinaryExpr::new(
            Arc::new(Column::new("a", 0)),
            Operator::Gt,
            Arc::new(Literal::new(ScalarValue::Int32(Some(0)))),
        ));
        let filter = FilterExecBuilder::new(predicate, input)
            .apply_projection(Some(vec![2]))?
            .build()?;

        // Output schema should be [c:Float64]
        let output_schema = filter.schema();
        assert_eq!(output_schema.fields().len(), 1);
        assert_eq!(output_schema.field(0).name(), "c");

        // Simulate a parent dynamic filter referencing output column c@0
        let parent_filter: Arc<dyn PhysicalExpr> = Arc::new(Column::new("c", 0));

        let config = ConfigOptions::new();
        let desc = filter.gather_filters_for_pushdown(
            FilterPushdownPhase::Post,
            vec![parent_filter],
            &config,
        )?;

        // The filter pushed to the child must reference c@2 (input schema),
        // not c@0 (output schema).
        let parent_filters = desc.parent_filters();
        assert_eq!(parent_filters.len(), 1); // one child
        assert_eq!(parent_filters[0].len(), 1); // one filter
        let remapped = &parent_filters[0][0].predicate;
        let display = format!("{remapped}");
        assert_eq!(
            display, "c@2",
            "Post-phase parent filter column index must be remapped \
             from output schema (c@0) to input schema (c@2)"
        );

        Ok(())
    }