Function verify_encoded_split

arrow-flight/src/encode.rs:2070–2111

Coverage for Encodes the specified batch using several values of `max_flight_data_size` between 1K to 5K and ensures that the resulting size of the flight data stays within the limit + `allowed_overage` `allowed_overage` is how far off the actual data encoding is from the target limit that was set. It is an improvement when the allowed_overage dec

(batch: RecordBatch, allowed_overage: usize)

    ///
    ///
    async fn verify_encoded_split(batch: RecordBatch, allowed_overage: usize) {
        let num_rows = batch.num_rows();

        // Track the overall required maximum overage
        let mut max_overage_seen = 0;

        for max_flight_data_size in [1024, 2021, 5000] {
            println!("Encoding {num_rows} with a maximum size of {max_flight_data_size}");

            let mut stream = FlightDataEncoderBuilder::new()
                .with_max_flight_data_size(max_flight_data_size)
                // use 8-byte alignment - default alignment is 64 which produces bigger ipc data
                .with_options(IpcWriteOptions::try_new(8, false, MetadataVersion::V5).unwrap())
                .build(futures::stream::iter([Ok(batch.clone())]));

            let mut i = 0;
            while let Some(data) = stream.next().await.transpose().unwrap() {
                let actual_data_size = flight_data_size(&data);

                let actual_overage = actual_data_size.saturating_sub(max_flight_data_size);

                assert!(
                    actual_overage <= allowed_overage,
                    "encoded data[{i}]: actual size {actual_data_size}, \
                         actual_overage: {actual_overage} \
                         allowed_overage: {allowed_overage}"
                );

                i += 1;

                max_overage_seen = max_overage_seen.max(actual_overage)
            }
        }

        // ensure that the specified overage is exactly the maxmium so
        // that when the splitting logic improves, the tests must be
        // updated to reflect the better logic
        assert_eq!(
            allowed_overage, max_overage_seen,
            "Specified overage was too high"
        );
    }
}