"""Shared fixtures for `Dispatcher` contract tests.

The `pair_factory` fixture parametrizes contract tests over every `Dispatcher`

implementation, so the same behavioral assertions run against `DirectDispatcher`

(in-memory) and `JSONRPCDispatcher` (over crossed anyio memory streams).

"""

from collections.abc import Callable

import anyio

import pytest

from mcp.shared.direct_dispatcher import create_direct_dispatcher_pair

from mcp.shared.dispatcher import Dispatcher

from mcp.shared.jsonrpc_dispatcher import JSONRPCDispatcher

from mcp.shared.message import SessionMessage

from mcp.shared.transport_context import TransportContext

DispatcherTriple = tuple[Dispatcher[TransportContext], Dispatcher[TransportContext], Callable[[], None]]

PairFactory = Callable[..., DispatcherTriple]

def direct_pair(*, can_send_request: bool = True) -> DispatcherTriple:

client, server = create_direct_dispatcher_pair(can_send_request=can_send_request)

def close() -> None:

client.close()

server.close()

return client, server, close

def jsonrpc_pair(*, can_send_request: bool = True) -> DispatcherTriple:

"""Two `JSONRPCDispatcher`s wired over crossed in-memory streams."""

c2s_send, c2s_recv = anyio.create_memory_object_stream[SessionMessage | Exception](32)

s2c_send, s2c_recv = anyio.create_memory_object_stream[SessionMessage | Exception](32)

def builder(_meta: object) -> TransportContext:

return TransportContext(kind="jsonrpc", can_send_request=can_send_request)

client: JSONRPCDispatcher[TransportContext] = JSONRPCDispatcher(s2c_recv, c2s_send, transport_builder=builder)

server: JSONRPCDispatcher[TransportContext] = JSONRPCDispatcher(c2s_recv, s2c_send, transport_builder=builder)

def close() -> None:

for s in (c2s_send, c2s_recv, s2c_send, s2c_recv):

s.close()

return client, server, close

@pytest.fixture(

params=[

pytest.param(direct_pair, id="direct"),

pytest.param(jsonrpc_pair, id="jsonrpc"),

]

)

def pair_factory(request: pytest.FixtureRequest) -> PairFactory:

return request.param

__all__ = ["PairFactory", "direct_pair", "jsonrpc_pair"]