test_r_core/

lib.rs

pub mod args;
pub mod bench;
mod execution;
pub mod internal;
mod ipc;
mod output;
mod panic_hook;
pub mod spawn;
mod stats;
#[cfg(feature = "tokio")]
mod tokio;
pub mod worker;

#[allow(dead_code)]
mod sync;

#[cfg(not(feature = "tokio"))]
pub use sync::test_runner;

#[cfg(feature = "tokio")]
pub use tokio::test_runner;

pub use worker::worker_index;

/// Re-export of [`desert_rust`] so that proc-macros emitted by
/// `test-r-macro` (e.g. [`test_r::hosted_rpc`]) can refer to it via
/// `::test_r::core::desert_rust::...` without forcing downstream
/// users to add `desert_rust` to their own `Cargo.toml`.
///
/// This is an internal support re-export — user code should not depend
/// on it being available at this path. The `#[doc(hidden)]` attribute
/// keeps it out of the rendered docs and signals that the surface
/// belongs to the macro support layer, not the public test-r API.
#[doc(hidden)]
pub use desert_rust;

// =====================================================================
// Hosted descriptor codec / worker reconstructor helpers.
//
// These two functions are the single place the descriptor-based Hosted
// dep wiring is built. The `tokio` cargo feature on `test-r-core`
// selects which variant of each function compiles, so that:
//
// - Under the **tokio** runtime, Hosted deps always use the *async*
//   path (`AsyncHostedDep::descriptor` / `from_descriptor`). Thanks to the
//   blanket `impl<T: HostedDep> AsyncHostedDep for T`, every sync `HostedDep`
//   automatically reaches the async path with no user-visible cost (the
//   bridged `from_descriptor` just wraps the sync impl in
//   `std::future::ready(...)`).
// - Under the **sync** runtime, Hosted deps always use the *sync* path
//   (`HostedDep::descriptor` / `from_descriptor`). This intentionally
//   keeps sync builds free of any block-poll machinery: a Hosted dep
//   that only implements `AsyncHostedDep` simply fails to compile
//   here, rather than panicking at runtime.
//
// The macro now emits a single uniform call to these helpers regardless
// of the (now deprecated) `async_worker` attribute; see
// `test-r-macro/src/deps.rs`.
// =====================================================================

/// **Hidden macro-support helper.**
///
/// Build the parent-side codec for a Hosted dep. Under the `tokio`
/// runtime this dispatches through [`internal::AsyncHostedDep`]; under
/// the sync runtime it dispatches through [`internal::HostedDep`]. The
/// returned [`internal::CloneableCodec`] knows how to:
///
/// - downcast the owner `Arc<dyn Any + Send + Sync>` back to `T` and
///   produce the descriptor bytes (`to_wire`), and
/// - turn raw descriptor bytes into a boxed payload that the matching
///   reconstructor below will hand off to `from_descriptor`
///   (`from_wire_bytes`).
///
/// Not part of the public API; only the proc-macro emits calls to it.
#[doc(hidden)]
#[cfg(feature = "tokio")]
pub fn __test_r_make_hosted_codec<T>() -> internal::CloneableCodec
where
    T: internal::AsyncHostedDep,
{
    use std::sync::Arc;
    internal::CloneableCodec {
        to_wire: Arc::new(|any: Arc<dyn std::any::Any + Send + Sync>| {
            let value: Arc<T> = any
                .downcast::<T>()
                .expect("Hosted dependency type mismatch in descriptor()");
            <T as internal::AsyncHostedDep>::descriptor(&*value)
        }),
        from_wire_bytes: Arc::new(|bytes: &[u8]| {
            // The "wire payload" for a Hosted dep is the raw descriptor
            // bytes; the matching reconstructor will run from_descriptor
            // against them on the worker side.
            let boxed: Arc<dyn std::any::Any + Send + Sync> = Arc::new(bytes.to_vec());
            boxed
        }),
    }
}

/// **Hidden macro-support helper.** Sync-runtime variant of
/// [`__test_r_make_hosted_codec`]; see that doc-comment.
#[doc(hidden)]
#[cfg(not(feature = "tokio"))]
pub fn __test_r_make_hosted_codec<T>() -> internal::CloneableCodec
where
    T: internal::HostedDep,
{
    use std::sync::Arc;
    internal::CloneableCodec {
        to_wire: Arc::new(|any: Arc<dyn std::any::Any + Send + Sync>| {
            let value: Arc<T> = any
                .downcast::<T>()
                .expect("Hosted dependency type mismatch in descriptor()");
            <T as internal::HostedDep>::descriptor(&*value)
        }),
        from_wire_bytes: Arc::new(|bytes: &[u8]| {
            let boxed: Arc<dyn std::any::Any + Send + Sync> = Arc::new(bytes.to_vec());
            boxed
        }),
    }
}

/// **Hidden macro-support helper.**
///
/// Build the worker-side [`internal::WorkerReconstructor`] for a Hosted
/// dep. Under the `tokio` runtime this returns an
/// [`internal::WorkerReconstructor::Async`] closure that awaits
/// [`internal::AsyncHostedDep::from_descriptor`]; under the sync
/// runtime it returns an [`internal::WorkerReconstructor::Sync`]
/// closure that calls [`internal::HostedDep::from_descriptor`].
///
/// The descriptor `Vec<u8>` is produced by the matching
/// [`__test_r_make_hosted_codec`] above; the two helpers must stay in
/// lockstep.
///
/// Not part of the public API; only the proc-macro emits calls to it.
#[doc(hidden)]
#[cfg(feature = "tokio")]
pub fn __test_r_make_hosted_worker_reconstructor<T>() -> internal::WorkerReconstructor
where
    T: internal::AsyncHostedDep,
{
    use std::sync::Arc;
    internal::WorkerReconstructor::Async(Arc::new(
        |wire_payload: Arc<dyn std::any::Any + Send + Sync>, _deps| {
            Box::pin(async move {
                let bytes: Arc<Vec<u8>> = wire_payload
                    .downcast::<Vec<u8>>()
                    .expect("Hosted worker reconstructor expected Vec<u8> descriptor payload");
                let value: T = <T as internal::AsyncHostedDep>::from_descriptor(&bytes).await;
                let boxed: Arc<dyn std::any::Any + Send + Sync> = Arc::new(value);
                boxed
            })
        },
    ))
}

/// **Hidden macro-support helper.** Sync-runtime variant of
/// [`__test_r_make_hosted_worker_reconstructor`]; see that
/// doc-comment.
#[doc(hidden)]
#[cfg(not(feature = "tokio"))]
pub fn __test_r_make_hosted_worker_reconstructor<T>() -> internal::WorkerReconstructor
where
    T: internal::HostedDep,
{
    use std::sync::Arc;
    internal::WorkerReconstructor::Sync(Arc::new(
        |wire_payload: Arc<dyn std::any::Any + Send + Sync>, _deps| {
            let bytes: Arc<Vec<u8>> = wire_payload
                .downcast::<Vec<u8>>()
                .expect("Hosted worker reconstructor expected Vec<u8> descriptor payload");
            let value: T = <T as internal::HostedDep>::from_descriptor(&bytes);
            let boxed: Arc<dyn std::any::Any + Send + Sync> = Arc::new(value);
            boxed
        },
    ))
}

// =====================================================================
// `worker = both(T)` helpers.
//
// `#[test_dep(scope = Hosted, worker = both(Trait))]` is lowered by the
// macro into two `RegisteredDependency` entries (one Hosted, one
// HostedRpc) that share a single parent-side owner via
// [`internal::HostedBothShared`]. The three helpers below centralize
// the shared logic:
//
// - `__test_r_make_hosted_both_shared::<T>(owner_arc, rpc_cell)` builds
//   the cell used by the macro's weak cache from an already-`Arc`'d
//   owner plus a prebuilt RPC cell. The macro acquire helper
//   constructs the `Arc<T>` once and shares it between this cell, the
//   RPC dispatch cell, and the parent-side owner getter — no second
//   owner instance, no `T: Clone` requirement. Cfg-selected on `tokio`
//   so the descriptor call uses `AsyncHostedDep::descriptor` under
//   tokio and `HostedDep::descriptor` under sync, mirroring the
//   single-view helpers.
// - `__test_r_make_hosted_both_codec()` produces the Hosted-view
//   codec; both bytes (`to_wire`) and payload (`from_wire_bytes`)
//   shapes match the existing single-view Hosted codec so the
//   runtime worker side stays unchanged.
// - `__test_r_make_hosted_both_rpc_factory::<T>()` produces the
//   HostedRpc-view factory. It downcasts the shared cell to extract
//   the inner `Arc<HostedRpcOwnerCell>`, and reuses the same
//   `build_stub(channel)` path the legacy HostedRpc factory uses.
// =====================================================================

/// **Hidden macro-support helper.** Build the shared owner cell for
/// a `worker = both(T)` dep from an already-`Arc`'d owner plus a
/// pre-built RPC cell. The macro acquire helper constructs `Arc<T>`
/// once and clones it into both this helper and the RPC cell so the
/// parent-side getter, the descriptor view, and the RPC dispatcher
/// observe exactly one owner instance.
///
/// Tokio variant: descriptor is computed via
/// [`internal::AsyncHostedDep::descriptor`].
#[doc(hidden)]
#[cfg(feature = "tokio")]
pub fn __test_r_make_hosted_both_shared<T>(
    owner: std::sync::Arc<T>,
    rpc_cell: std::sync::Arc<internal::HostedRpcOwnerCell>,
) -> internal::HostedBothShared
where
    T: internal::AsyncHostedDep,
{
    use std::sync::Arc;
    let descriptor_bytes = <T as internal::AsyncHostedDep>::descriptor(&*owner);
    let owner_any: Arc<dyn std::any::Any + Send + Sync> = owner;
    internal::HostedBothShared::new(descriptor_bytes, owner_any, rpc_cell)
}

/// **Hidden macro-support helper.** Sync-runtime variant of
/// [`__test_r_make_hosted_both_shared`]; descriptor is computed via
/// [`internal::HostedDep::descriptor`].
#[doc(hidden)]
#[cfg(not(feature = "tokio"))]
pub fn __test_r_make_hosted_both_shared<T>(
    owner: std::sync::Arc<T>,
    rpc_cell: std::sync::Arc<internal::HostedRpcOwnerCell>,
) -> internal::HostedBothShared
where
    T: internal::HostedDep,
{
    use std::sync::Arc;
    let descriptor_bytes = <T as internal::HostedDep>::descriptor(&*owner);
    let owner_any: Arc<dyn std::any::Any + Send + Sync> = owner;
    internal::HostedBothShared::new(descriptor_bytes, owner_any, rpc_cell)
}

/// **Hidden macro-support helper.** Wrap a HostedRpc owner value into a
/// [`internal::HostedRpcOwnerCell`]. The tokio variant goes through
/// [`internal::HostedRpcOwnerCell::from_async_owner`] so async owners
/// are dispatched asynchronously; the sync variant uses the back-compat
/// sync constructor. Used by the `#[test_dep(scope = HostedRpc)]`
/// lowering so the choice of async vs sync cell happens in one place.
#[doc(hidden)]
#[cfg(feature = "tokio")]
pub fn __test_r_make_hosted_rpc_cell<T>(owner: T) -> internal::HostedRpcOwnerCell
where
    T: internal::AsyncHostedRpcDep,
{
    internal::HostedRpcOwnerCell::from_async_owner(owner)
}

/// **Hidden macro-support helper.** Sync-runtime variant of
/// [`__test_r_make_hosted_rpc_cell`].
#[doc(hidden)]
#[cfg(not(feature = "tokio"))]
pub fn __test_r_make_hosted_rpc_cell<T>(owner: T) -> internal::HostedRpcOwnerCell
where
    T: internal::HostedRpcDep,
{
    internal::HostedRpcOwnerCell::from_owner(owner)
}

/// **Hidden macro-support helper.** Hosted-view codec for the `both`
/// variant. Wire format is identical to the existing single-view
/// Hosted codec so the worker reconstructor (still
/// [`__test_r_make_hosted_worker_reconstructor`]) stays unchanged.
#[doc(hidden)]
pub fn __test_r_make_hosted_both_codec() -> internal::CloneableCodec {
    use std::any::Any;
    use std::sync::Arc;
    internal::CloneableCodec {
        to_wire: Arc::new(|any: Arc<dyn Any + Send + Sync>| {
            let shared: Arc<internal::HostedBothShared> = any
                .downcast::<internal::HostedBothShared>()
                .expect("HostedBothShared downcast failed in both-codec to_wire");
            shared.descriptor_bytes().to_vec()
        }),
        from_wire_bytes: Arc::new(|bytes: &[u8]| {
            // Same payload shape as the single-view Hosted codec: a
            // boxed `Vec<u8>` for the worker reconstructor to consume.
            let boxed: Arc<dyn Any + Send + Sync> = Arc::new(bytes.to_vec());
            boxed
        }),
    }
}

/// **Hidden macro-support helper.** HostedRpc-view factory for the
/// `both` variant. Pulls the inner `Arc<HostedRpcOwnerCell>` out of
/// the shared cell and reuses the user's
/// [`internal::HostedRpcDep::build_stub`] for the worker stub.
#[doc(hidden)]
#[cfg(feature = "tokio")]
pub fn __test_r_make_hosted_both_rpc_factory<T, Stub>() -> internal::RpcFactory
where
    T: internal::AsyncHostedRpcDep<Stub = Stub>,
    Stub: Send + Sync + 'static,
{
    use std::any::Any;
    use std::sync::Arc;
    internal::RpcFactory {
        owner_into_cell: Arc::new(|any: Arc<dyn Any + Send + Sync>| {
            let shared: Arc<internal::HostedBothShared> = any
                .downcast::<internal::HostedBothShared>()
                .expect("HostedBothShared downcast failed in both-rpc-factory owner_into_cell");
            shared.rpc_cell()
        }),
        build_stub: Arc::new(|channel: internal::HostedRpcChannel| {
            let stub: Stub = <T as internal::AsyncHostedRpcDep>::build_stub(channel);
            let boxed: Arc<dyn Any + Send + Sync> = Arc::new(stub);
            boxed
        }),
    }
}

/// **Hidden macro-support helper.** Sync-runtime variant of
/// [`__test_r_make_hosted_both_rpc_factory`]. The `build_stub` is sourced
/// from [`internal::HostedRpcDep::build_stub`] because the sync runtime
/// cannot drive `AsyncHostedRpcDep` owners.
#[doc(hidden)]
#[cfg(not(feature = "tokio"))]
pub fn __test_r_make_hosted_both_rpc_factory<T, Stub>() -> internal::RpcFactory
where
    T: internal::HostedRpcDep<Stub = Stub>,
    Stub: Send + Sync + 'static,
{
    use std::any::Any;
    use std::sync::Arc;
    internal::RpcFactory {
        owner_into_cell: Arc::new(|any: Arc<dyn Any + Send + Sync>| {
            let shared: Arc<internal::HostedBothShared> = any
                .downcast::<internal::HostedBothShared>()
                .expect("HostedBothShared downcast failed in both-rpc-factory owner_into_cell");
            shared.rpc_cell()
        }),
        build_stub: Arc::new(|channel: internal::HostedRpcChannel| {
            let stub: Stub = <T as internal::HostedRpcDep>::build_stub(channel);
            let boxed: Arc<dyn Any + Send + Sync> = Arc::new(stub);
            boxed
        }),
    }
}

/// **Hidden macro-support helper.** Build a `RpcFactory` for the
/// stand-alone `scope = HostedRpc` lowering (no `both(T)` companion).
/// Tokio variant goes through [`internal::AsyncHostedRpcDep::build_stub`]
/// so async owners flow through one entry point.
#[doc(hidden)]
#[cfg(feature = "tokio")]
pub fn __test_r_make_hosted_rpc_factory<T, Stub>() -> internal::RpcFactory
where
    T: internal::AsyncHostedRpcDep<Stub = Stub>,
    Stub: Send + Sync + 'static,
{
    use std::any::Any;
    use std::sync::Arc;
    internal::RpcFactory {
        owner_into_cell: Arc::new(|any: Arc<dyn Any + Send + Sync>| {
            any.downcast::<internal::HostedRpcOwnerCell>()
                .expect("HostedRpc owner downcast to HostedRpcOwnerCell failed")
        }),
        build_stub: Arc::new(|channel: internal::HostedRpcChannel| {
            let stub: Stub = <T as internal::AsyncHostedRpcDep>::build_stub(channel);
            let boxed: Arc<dyn Any + Send + Sync> = Arc::new(stub);
            boxed
        }),
    }
}

/// **Hidden macro-support helper.** Sync-runtime variant of
/// [`__test_r_make_hosted_rpc_factory`].
#[doc(hidden)]
#[cfg(not(feature = "tokio"))]
pub fn __test_r_make_hosted_rpc_factory<T, Stub>() -> internal::RpcFactory
where
    T: internal::HostedRpcDep<Stub = Stub>,
    Stub: Send + Sync + 'static,
{
    use std::any::Any;
    use std::sync::Arc;
    internal::RpcFactory {
        owner_into_cell: Arc::new(|any: Arc<dyn Any + Send + Sync>| {
            any.downcast::<internal::HostedRpcOwnerCell>()
                .expect("HostedRpc owner downcast to HostedRpcOwnerCell failed")
        }),
        build_stub: Arc::new(|channel: internal::HostedRpcChannel| {
            let stub: Stub = <T as internal::HostedRpcDep>::build_stub(channel);
            let boxed: Arc<dyn Any + Send + Sync> = Arc::new(stub);
            boxed
        }),
    }
}

#[cfg(test)]
mod hosted_helper_tests {
    //! Exercise the feature-gated
    //! [`__test_r_make_hosted_codec`] /
    //! [`__test_r_make_hosted_worker_reconstructor`] helpers end to
    //! end against a tiny `HostedDep` fixture.
    //!
    //! Both helper variants must reject `WorkerReconstructor::Sync`
    //! vs `Async` choice at the cargo-feature level, so we keep this
    //! test cfg-aware: it asserts the matching variant under each
    //! feature.
    use super::*;
    use std::any::Any;
    use std::sync::Arc;

    /// Minimal sync `HostedDep` fixture. Under the `tokio` feature
    /// the blanket bridge also makes it `AsyncHostedDep`, so the same fixture
    /// is usable against both helper variants.
    #[derive(Debug, PartialEq, Eq)]
    struct Fixture {
        bytes: Vec<u8>,
    }

    impl internal::HostedDep for Fixture {
        fn descriptor(&self) -> Vec<u8> {
            self.bytes.clone()
        }
        fn from_descriptor(bytes: &[u8]) -> Self {
            Self {
                bytes: bytes.to_vec(),
            }
        }
    }

    #[test]
    fn make_hosted_codec_round_trips_descriptor_bytes() {
        let codec = __test_r_make_hosted_codec::<Fixture>();
        let owner: Arc<dyn Any + Send + Sync> = Arc::new(Fixture {
            bytes: vec![1, 2, 3, 4],
        });

        let wire_bytes = (codec.to_wire)(owner);
        assert_eq!(wire_bytes, vec![1, 2, 3, 4]);

        let wire_payload = (codec.from_wire_bytes)(&wire_bytes);
        let recovered_bytes: Arc<Vec<u8>> = wire_payload
            .downcast::<Vec<u8>>()
            .expect("from_wire_bytes must produce Arc<Vec<u8>>");
        assert_eq!(*recovered_bytes, vec![1, 2, 3, 4]);
    }

    /// Under the tokio runtime, the worker reconstructor helper must
    /// return [`internal::WorkerReconstructor::Async`].
    #[cfg(feature = "tokio")]
    #[test]
    fn make_hosted_worker_reconstructor_is_async_under_tokio() {
        let recon = __test_r_make_hosted_worker_reconstructor::<Fixture>();
        match recon {
            internal::WorkerReconstructor::Async(_) => {}
            internal::WorkerReconstructor::Sync(_) => panic!(
                "tokio build must produce a WorkerReconstructor::Async for Hosted deps; got Sync"
            ),
        }
    }

    /// Under the sync runtime, the worker reconstructor helper must
    /// return [`internal::WorkerReconstructor::Sync`] so the sync
    /// runner can drive it without any block-poll machinery.
    #[cfg(not(feature = "tokio"))]
    #[test]
    fn make_hosted_worker_reconstructor_is_sync_under_sync_runtime() {
        let recon = __test_r_make_hosted_worker_reconstructor::<Fixture>();
        match recon {
            internal::WorkerReconstructor::Sync(_) => {}
            internal::WorkerReconstructor::Async(_) => panic!(
                "sync build must produce a WorkerReconstructor::Sync for Hosted deps; got Async"
            ),
        }
    }

    /// Drive the sync-runtime reconstructor closure end to end on
    /// the matching descriptor bytes the codec produces. Pinned only
    /// for the sync build because the tokio build returns an Async
    /// closure that needs a runtime to await.
    #[cfg(not(feature = "tokio"))]
    #[test]
    fn sync_worker_reconstructor_rebuilds_fixture_from_descriptor() {
        // Re-use a small `DependencyView` impl: the helper's worker
        // closure ignores the view, so we pass an empty stub.
        #[derive(Debug)]
        struct EmptyView;
        impl internal::DependencyView for EmptyView {
            fn get(&self, _name: &str) -> Option<Arc<dyn Any + Send + Sync>> {
                None
            }
        }

        let codec = __test_r_make_hosted_codec::<Fixture>();
        let recon = __test_r_make_hosted_worker_reconstructor::<Fixture>();

        let owner: Arc<dyn Any + Send + Sync> = Arc::new(Fixture {
            bytes: vec![5, 6, 7],
        });
        let wire_bytes = (codec.to_wire)(owner);
        let payload = (codec.from_wire_bytes)(&wire_bytes);

        let deps: Arc<dyn internal::DependencyView + Send + Sync> = Arc::new(EmptyView);
        let rebuilt = match recon {
            internal::WorkerReconstructor::Sync(f) => f(payload, deps),
            internal::WorkerReconstructor::Async(_) => unreachable!(
                "sync build cannot return Async; pinned by \
                 make_hosted_worker_reconstructor_is_sync_under_sync_runtime",
            ),
        };
        let rebuilt: Arc<Fixture> = rebuilt
            .downcast::<Fixture>()
            .expect("worker reconstructor must produce the original Hosted dep type");
        assert_eq!(
            *rebuilt,
            Fixture {
                bytes: vec![5, 6, 7]
            }
        );
    }

    // -----------------------------------------------------------------
    // `worker = both(T)` helper tests.
    //
    // The macro lowering for `#[test_dep(scope = Hosted, worker =
    // both(Trait))]` is exercised end-to-end by the
    // `sharing::hosted_both_basic` example fixtures. These unit tests
    // pin the three pieces of cargo-feature-aware glue in this file:
    //
    // - `__test_r_make_hosted_both_shared::<T>(owner_arc, rpc_cell)`
    //   builds the shared cell that the macro's weak cache hands back
    //   to both the Hosted and HostedRpc registrations, from an
    //   already-`Arc`'d owner and the prebuilt
    //   [`internal::HostedRpcOwnerCell`] the macro produces.
    // - `__test_r_make_hosted_both_codec()` serializes the cached
    //   descriptor bytes for the Hosted view.
    // - `__test_r_make_hosted_both_rpc_factory::<T>()` extracts the
    //   inner `Arc<HostedRpcOwnerCell>` for the HostedRpc view and
    //   builds the worker-side stub via `HostedRpcDep::build_stub`.
    // -----------------------------------------------------------------

    /// Minimal `HostedDep + HostedRpcDep` fixture for helper tests. The id
    /// allocator stands in for any tiny control surface; the bytes field doubles
    /// as the descriptor.
    #[derive(Debug)]
    struct BothFixture {
        bytes: Vec<u8>,
        counter: std::sync::Mutex<u64>,
    }

    impl BothFixture {
        fn new(bytes: Vec<u8>) -> Self {
            Self {
                bytes,
                counter: std::sync::Mutex::new(0),
            }
        }
    }

    impl internal::HostedDep for BothFixture {
        fn descriptor(&self) -> Vec<u8> {
            self.bytes.clone()
        }
        fn from_descriptor(bytes: &[u8]) -> Self {
            Self::new(bytes.to_vec())
        }
    }

    /// Stub view for the BothFixture. Holds a HostedRpcChannel so a
    /// realistic build_stub round-trip is exercised; the tests below
    /// just verify the factory hands back a usable `Arc<BothStub>`,
    /// not a full IPC round-trip (covered by the example fixtures).
    pub struct BothStub {
        _channel: internal::HostedRpcChannel,
    }

    impl internal::HostedRpcDep for BothFixture {
        type Stub = BothStub;
        fn dispatch(&mut self, method_idx: u32, args: &[u8]) -> Result<Vec<u8>, String> {
            // Delegate to the shared `&self` dispatcher so the same
            // implementation services both the legacy `from_owner`
            // path (which expects `&mut self`) and the new
            // `from_shared_owner_*` path (which expects `&self`).
            // Mirrors the shape of what `#[hosted_rpc]`'s
            // blanket-implemented dispatcher will look like once we
            // add the shared variant.
            #[cfg(feature = "tokio")]
            {
                futures::executor::block_on(Self::dispatch_shared(self, method_idx, args))
            }
            #[cfg(not(feature = "tokio"))]
            {
                Self::dispatch_shared(self, method_idx, args)
            }
        }
        fn build_stub(channel: internal::HostedRpcChannel) -> Self::Stub {
            BothStub { _channel: channel }
        }
    }

    impl BothFixture {
        /// `&self`-receiver dispatcher used by the shared-owner cell
        /// (`from_shared_owner_sync` / `from_shared_owner_async`). The
        /// sync runtime returns a plain `Result`; the tokio runtime
        /// wraps it in an `async fn` so the same body satisfies the
        /// `Pin<Box<dyn Future + Send + 'a>>` closure shape.
        #[cfg(not(feature = "tokio"))]
        fn dispatch_shared(this: &Self, method_idx: u32, _args: &[u8]) -> Result<Vec<u8>, String> {
            if method_idx == 1 {
                let mut g = this.counter.lock().map_err(|e| e.to_string())?;
                *g += 1;
                Ok(g.to_be_bytes().to_vec())
            } else {
                Err(format!("BothFixture: unknown method_idx {method_idx}"))
            }
        }

        /// Tokio variant of [`Self::dispatch_shared`]. Returning an
        /// `async fn` lets the boxed-future closure used by
        /// [`internal::HostedRpcOwnerCell::from_shared_owner_async`]
        /// hold the resulting future for the duration of the call.
        #[cfg(feature = "tokio")]
        async fn dispatch_shared(
            this: &Self,
            method_idx: u32,
            _args: &[u8],
        ) -> Result<Vec<u8>, String> {
            if method_idx == 1 {
                let mut g = this.counter.lock().map_err(|e| e.to_string())?;
                *g += 1;
                Ok(g.to_be_bytes().to_vec())
            } else {
                Err(format!("BothFixture: unknown method_idx {method_idx}"))
            }
        }
    }

    /// Build a `HostedBothShared` cell for tests in the shape the new
    /// macro acquire helper produces: one `Arc<T>` owner shared
    /// between the cell and the descriptor view, with a closure-based
    /// shared-owner cell so dispatch routes against `&T`. Used by the
    /// helper tests below so they don't have to repeat the closure
    /// glue, and so the parent-side `owner_arc::<T>()` accessor sees
    /// the exact same `Arc<T>` the cell holds.
    fn build_both_shared_for_test(
        owner: BothFixture,
    ) -> (Arc<BothFixture>, internal::HostedBothShared) {
        let owner_arc = Arc::new(owner);
        let cell_arc = build_both_rpc_cell_for_test(owner_arc.clone());
        let shared = __test_r_make_hosted_both_shared::<BothFixture>(owner_arc.clone(), cell_arc);
        (owner_arc, shared)
    }

    /// Build the shared `Arc<HostedRpcOwnerCell>` for the test
    /// fixture. The closure delegates to the fixture's
    /// `dispatch_shared` (a tiny `&self` dispatcher that mirrors what
    /// `#[hosted_rpc]` will generate via `dispatch_<snake>_shared`).
    /// Cargo-feature-aware so the same construction works under sync
    /// and tokio runtimes.
    fn build_both_rpc_cell_for_test(owner: Arc<BothFixture>) -> Arc<internal::HostedRpcOwnerCell> {
        #[cfg(feature = "tokio")]
        {
            Arc::new(internal::HostedRpcOwnerCell::from_shared_owner_async(
                owner,
                |o, idx, args| Box::pin(BothFixture::dispatch_shared(o, idx, args)),
            ))
        }
        #[cfg(not(feature = "tokio"))]
        {
            Arc::new(internal::HostedRpcOwnerCell::from_shared_owner_sync(
                owner,
                |o, idx, args| BothFixture::dispatch_shared(o, idx, args),
            ))
        }
    }

    /// `__test_r_make_hosted_both_shared(owner_arc, rpc_cell)` captures
    /// the owner's descriptor bytes once and stitches together the
    /// shared `Arc<T>` with the prebuilt `HostedRpcOwnerCell`. The
    /// captured descriptor must match the owner's `HostedDep::descriptor()`
    /// (or `AsyncHostedDep::descriptor()` under tokio) output exactly.
    #[test]
    fn make_hosted_both_shared_captures_descriptor_bytes() {
        let (_owner, shared) = build_both_shared_for_test(BothFixture::new(vec![10, 20, 30]));
        assert_eq!(shared.descriptor_bytes(), &[10, 20, 30]);
        // The owner cell must be live: a dispatch call must succeed
        // (the closure runs the method without panicking and returns
        // a non-empty reply). Under the tokio feature the cell is the
        // async variant — drive it through `dispatch_async` on a
        // tokio runtime; under the sync feature the cell is sync.
        let reply =
            dispatch_cell_for_test(&shared.rpc_cell(), 1, &[]).expect("dispatch must succeed");
        assert_eq!(reply, 1u64.to_be_bytes().to_vec());
    }

    /// The owner the cell dispatches against must be the exact same
    /// `Arc<T>` the parent-side getter would return. This pins the
    /// regression fix for the bug where `worker = both(...)` made the
    /// parent dep map hold an `Arc<HostedBothShared>` while the
    /// generated owner getter expected `Arc<T>` and panicked.
    #[test]
    fn make_hosted_both_shared_exposes_owner_arc() {
        let (owner_arc, shared) = build_both_shared_for_test(BothFixture::new(vec![42]));
        let recovered = shared.owner_arc::<BothFixture>();
        assert!(
            Arc::ptr_eq(&owner_arc, &recovered),
            "owner_arc::<T>() must return the very same Arc the cell holds"
        );
        // A round trip through the cell observes the same owner via
        // the shared counter that owner_arc points at.
        let _ = dispatch_cell_for_test(&shared.rpc_cell(), 1, &[]).expect("dispatch must succeed");
        let observed = *recovered
            .counter
            .lock()
            .expect("BothFixture counter must not be poisoned");
        assert_eq!(
            observed, 1,
            "the cell must mutate the same owner the parent getter would hand out, observed {observed}"
        );
    }

    /// Helper: dispatch on a `HostedRpcOwnerCell` whose async/sync
    /// variant depends on the active cargo feature. Used by the
    /// `worker = both(T)` helper tests so the test bodies don't need
    /// to know whether the cell was built via `from_owner` or
    /// `from_async_owner` — both surface the same per-call result.
    fn dispatch_cell_for_test(
        cell: &internal::HostedRpcOwnerCell,
        method_idx: u32,
        args: &[u8],
    ) -> Result<Vec<u8>, String> {
        #[cfg(feature = "tokio")]
        {
            // `tokio` resolves to the local `mod tokio` inside this
            // crate; reach the external crate with `::tokio`.
            let rt = ::tokio::runtime::Builder::new_multi_thread()
                .enable_all()
                .build()
                .expect("build tokio runtime");
            rt.block_on(cell.dispatch_async(method_idx, args))
        }
        #[cfg(not(feature = "tokio"))]
        {
            cell.dispatch(method_idx, args)
        }
    }

    /// `__test_r_make_hosted_both_codec().to_wire` downcasts the
    /// shared cell and returns its captured descriptor bytes — the
    /// same shape the worker-side reconstructor expects.
    #[test]
    fn make_hosted_both_codec_serializes_descriptor_bytes() {
        let codec = __test_r_make_hosted_both_codec();
        let (_owner, shared) = build_both_shared_for_test(BothFixture::new(vec![1, 2, 3, 4]));
        let shared = Arc::new(shared);
        let arc_any: Arc<dyn Any + Send + Sync> = shared;

        let wire_bytes = (codec.to_wire)(arc_any);
        assert_eq!(wire_bytes, vec![1, 2, 3, 4]);

        // `from_wire_bytes` must produce the same `Arc<Vec<u8>>`
        // payload shape the existing Hosted reconstructor consumes —
        // otherwise the worker side would not be able to reuse the
        // standard `__test_r_make_hosted_worker_reconstructor`.
        let wire_payload = (codec.from_wire_bytes)(&wire_bytes);
        let recovered_bytes: Arc<Vec<u8>> = wire_payload
            .downcast::<Vec<u8>>()
            .expect("from_wire_bytes must produce Arc<Vec<u8>>");
        assert_eq!(*recovered_bytes, vec![1, 2, 3, 4]);
    }

    /// `__test_r_make_hosted_both_rpc_factory::<T, Stub>().owner_into_cell`
    /// reaches into the shared cell, hands back the inner
    /// `Arc<HostedRpcOwnerCell>`, and a dispatched call hits the
    /// real owner (proven by the counter incrementing).
    #[test]
    fn make_hosted_both_rpc_factory_extracts_owner_cell() {
        let factory = __test_r_make_hosted_both_rpc_factory::<BothFixture, BothStub>();
        let (_owner, shared) = build_both_shared_for_test(BothFixture::new(vec![]));
        let shared = Arc::new(shared);
        let arc_any: Arc<dyn Any + Send + Sync> = shared.clone();

        let cell = (factory.owner_into_cell)(arc_any);
        assert!(
            Arc::ptr_eq(&cell, &shared.rpc_cell()),
            "factory must return the exact same inner HostedRpcOwnerCell Arc the \
             shared cell holds; otherwise the RPC view would dispatch against a \
             different owner than the descriptor view captured"
        );

        // The cell is functional: dispatch routes to the real owner
        // method (counter starts at 0; first call must yield 1). Same
        // cargo-feature-aware dispatch as
        // `make_hosted_both_shared_captures_descriptor_bytes` since the
        // underlying cell shares the same async/sync split.
        let reply = dispatch_cell_for_test(&cell, 1, &[]).expect("dispatch must succeed");
        assert_eq!(reply, 1u64.to_be_bytes().to_vec());
    }

    /// `__test_r_make_hosted_both_rpc_factory::<T, Stub>().build_stub`
    /// constructs a worker-side `Stub` via the user's
    /// `HostedRpcDep::build_stub` and boxes it as `Arc<dyn Any>` so
    /// the runtime can route it through the standard dep view.
    #[test]
    fn make_hosted_both_rpc_factory_builds_stub() {
        use internal::{HostedRpcChannel, HostedRpcError, HostedRpcTransport};

        // Minimal in-process transport stand-in: every call returns
        // the unit reply. We don't actually call into it; the test
        // just exercises that build_stub produces a downcastable
        // `Arc<dyn Any>` carrying the channel.
        struct DummyTransport;
        impl HostedRpcTransport for DummyTransport {
            fn call(
                &self,
                _dep_id: &str,
                _method_idx: u32,
                _args: Vec<u8>,
            ) -> Result<Vec<u8>, HostedRpcError> {
                Ok(Vec::new())
            }
        }

        let factory = __test_r_make_hosted_both_rpc_factory::<BothFixture, BothStub>();
        let transport: Arc<dyn HostedRpcTransport> = Arc::new(DummyTransport);
        let channel = HostedRpcChannel::new("test::both_fixture".to_string(), transport);

        let stub_any: Arc<dyn Any + Send + Sync> = (factory.build_stub)(channel);
        let _stub: Arc<BothStub> = stub_any
            .downcast::<BothStub>()
            .expect("build_stub must produce the BothFixture::Stub type");
    }
}