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chore: import upstream snapshot with attribution
2026-07-13 12:10:27 +08:00

117 lines
4.5 KiB
Python

"""Regression coverage for the StreamableHTTP per-session response router."""
import anyio
import pytest
from mcp_types import JSONRPCMessage, JSONRPCResponse
from starlette.types import Message, Scope
from mcp.server.streamable_http import (
REQUEST_STREAM_BUFFER_SIZE,
EventCallback,
EventId,
EventMessage,
EventStore,
StreamableHTTPServerTransport,
StreamId,
)
from mcp.shared.message import SessionMessage
class _PrimingFailingStore(EventStore):
async def store_event(self, stream_id: StreamId, message: JSONRPCMessage | None) -> EventId:
raise RuntimeError("backend unavailable")
async def replay_events_after(self, last_event_id: EventId, send_callback: EventCallback) -> StreamId | None:
raise NotImplementedError
@pytest.mark.anyio
async def test_router_unconsumed_request_stream_does_not_block_siblings() -> None:
"""A response whose `sse_writer` is not yet receiving must not park the router (#1764).
Drives the routing layer directly (the production race does not reproduce
on loopback), so this pins the router semantics, not the call sites.
"""
transport = StreamableHTTPServerTransport(mcp_session_id="sid", is_json_response_enabled=False)
streams = transport._request_streams
async with transport.connect() as (_read_stream, write_stream):
# Model two concurrent POSTs at the point _handle_post_request has
# registered the per-request stream but A's sse_writer has not yet
# reached its first receive().
streams["A"] = anyio.create_memory_object_stream[EventMessage](REQUEST_STREAM_BUFFER_SIZE)
streams["B"] = anyio.create_memory_object_stream[EventMessage](REQUEST_STREAM_BUFFER_SIZE)
a_send, a_recv = streams["A"]
b_reader = streams["B"][1]
b_received = anyio.Event()
async def consume_b() -> None:
async with b_reader:
await b_reader.receive()
b_received.set()
async def server_writes() -> None:
await write_stream.send(SessionMessage(JSONRPCResponse(jsonrpc="2.0", id="A", result={})))
await write_stream.send(SessionMessage(JSONRPCResponse(jsonrpc="2.0", id="B", result={})))
async with anyio.create_task_group() as tg:
tg.start_soon(consume_b)
tg.start_soon(server_writes)
with anyio.fail_after(5):
await b_received.wait()
# A's response was buffered for its (late) consumer, not dropped.
assert a_send.statistics().current_buffer_used == 1
await a_recv.aclose()
await a_send.aclose()
@pytest.mark.anyio
async def test_priming_store_failure_leaves_no_per_request_state() -> None:
"""`EventStore.store_event` raising on the priming row must not leak per-request entries."""
transport = StreamableHTTPServerTransport(
mcp_session_id=None,
is_json_response_enabled=False,
event_store=_PrimingFailingStore(),
)
body = b'{"jsonrpc":"2.0","id":"req-1","method":"tools/list","params":{}}'
scope: Scope = {
"type": "http",
"method": "POST",
"path": "/",
"query_string": b"",
"headers": [
(b"accept", b"application/json, text/event-stream"),
(b"content-type", b"application/json"),
(b"mcp-protocol-version", b"2025-11-25"),
],
}
body_sent = False
async def receive() -> Message:
nonlocal body_sent
if not body_sent:
body_sent = True
return {"type": "http.request", "body": body, "more_body": False}
raise NotImplementedError
sent: list[Message] = []
async def asgi_send(message: Message) -> None:
sent.append(message)
async with transport.connect() as (read_stream, _write_stream):
async with anyio.create_task_group() as tg:
tg.start_soon(transport.handle_request, scope, receive, asgi_send)
with anyio.fail_after(5):
forwarded = await read_stream.receive()
assert isinstance(forwarded, Exception)
# handle_request has returned; connect()'s finally (which clears
# _request_streams unconditionally) has not yet run.
assert transport._request_streams == {}
assert transport._sse_stream_writers == {}
assert sent[0]["type"] == "http.response.start"
assert sent[0]["status"] == 500
body = b"".join(m.get("body", b"") for m in sent if m["type"] == "http.response.body")
assert b"backend unavailable" not in body