swactor/crates/distribution/tests/transport_and_codec.rs

use distribution::messages::*;
use distribution::swim::actor::SwimIn;
use distribution::types::NodeId;
use std::any::TypeId;

// ─── Codec registry ─────────────────────────────────────────────────────────

#[test]
fn distribution_codec_encodes_and_decodes_ping() {
    let codecs = distribution_codec_registry();
    let ping = Ping {
        from: NodeId([0xAA; 32]),
        sequence: 42,
        piggyback: vec![],
    };

    let type_id = std::any::TypeId::of::<Ping>();
    let (tag, bytes) = codecs.encode(type_id, Box::new(ping.clone())).unwrap();
    assert_eq!(&tag, "swactor_dist::Ping");

    let decoded_any = codecs.decode(&tag, &bytes).unwrap();
    let decoded: &Ping = decoded_any.downcast_ref().unwrap();
    assert_eq!(decoded.from, ping.from);
    assert_eq!(decoded.sequence, ping.sequence);
}

#[test]
fn all_message_types_registered_in_codec_registry() {
    let codecs = distribution_codec_registry();

    let tags = [
        "swactor_dist::Ping",
        "swactor_dist::Ack",
        "swactor_dist::PingReq",
        "swactor_dist::JoinRequest",
        "swactor_dist::JoinResponse",
        "swactor_dist::RegistryGossip",
        "swactor_dist::MetadataGossip",
        "swactor_dist::DirectoryGossip",
    ];

    for tag in tags {
        let result = codecs.decode(tag, &[]);
        let err = result.unwrap_err();
        let err_str = format!("{}", err);
        assert!(
            !err_str.contains("unknown type_tag"),
            "Decoder not registered for tag '{tag}': {err_str}"
        );
    }
}

// ─── Actor transport registry: wire tag ⇄ SwimIn variant ─────────────────────

/// A SWIM message sent as a `SwimIn` variant encodes to its concrete wire tag,
/// and a frame on that tag decodes back into the *same* `SwimIn` variant — so
/// the egress (`ctx.send(SwimIn::Ping)`) and ingress (`deliver_raw(SwimIn::Ping)`)
/// halves agree on the wire format without anyone hand-dispatching by tag.
#[test]
fn actor_registry_round_trips_swim_in_through_its_wire_tag() {
    let codecs = actor_codec_registry();
    let ping = Ping {
        from: NodeId([0xCD; 32]),
        sequence: 7,
        piggyback: vec![1, 2, 3],
    };

    // Egress: a SwimIn variant encodes by its TypeId to the concrete wire tag.
    let (tag, bytes) = codecs
        .encode(TypeId::of::<SwimIn>(), Box::new(SwimIn::Ping(ping.clone())))
        .expect("SwimIn::Ping encodes");
    assert_eq!(&tag, "swactor_dist::Ping");

    // Ingress: that frame decodes back into a SwimIn (not the bare Ping), ready
    // to deliver_raw straight into the SwimActor's mailbox.
    let decoded = codecs.decode(&tag, &bytes).expect("frame decodes");
    match decoded.downcast_ref::<SwimIn>() {
        Some(SwimIn::Ping(p)) => {
            assert_eq!(p.from, ping.from);
            assert_eq!(p.sequence, ping.sequence);
            assert_eq!(p.piggyback, ping.piggyback);
        }
        _ => panic!("expected the frame to decode into SwimIn::Ping"),
    }
}

/// Local-control variants (`Tick`, `Subscribe`, …) are not part of the wire
/// protocol; they must never serialize, so an accidental `ctx.send` of one to a
/// remote peer fails loudly at the encode boundary rather than shipping garbage.
#[test]
fn actor_registry_refuses_to_encode_local_only_variants() {
    let codecs = actor_codec_registry();
    for local in [SwimIn::Leave, SwimIn::Join { seeds: vec![] }] {
        let err = codecs
            .encode(TypeId::of::<SwimIn>(), Box::new(local))
            .expect_err("local-only SwimIn variant must not encode");
        assert!(
            format!("{err}").contains("local-only"),
            "unexpected error: {err}"
        );
    }
}

/// Registry/metadata gossip are standalone wire frames (no longer piggybacked on
/// SWIM); confirm they survive a JSON round-trip through the shared registry.
#[test]
fn registry_and_metadata_gossip_round_trip() {
    let codecs = distribution_codec_registry();

    let rg = RegistryGossip { entries: vec![] };
    let (tag, bytes) = codecs
        .encode(TypeId::of::<RegistryGossip>(), Box::new(rg))
        .unwrap();
    assert_eq!(&tag, "swactor_dist::RegistryGossip");
    assert!(codecs.decode(&tag, &bytes).unwrap().is::<RegistryGossip>());

    let mg = MetadataGossip { entries: vec![] };
    let (tag, bytes) = codecs
        .encode(TypeId::of::<MetadataGossip>(), Box::new(mg))
        .unwrap();
    assert_eq!(&tag, "swactor_dist::MetadataGossip");
    assert!(codecs.decode(&tag, &bytes).unwrap().is::<MetadataGossip>());
}