Files
modelcontextprotocol--pytho…/tests/server/test_connection.py
T
wehub-resource-sync 49b9bb6724
Deploy Docs / deploy-docs (push) Failing after 1s
Conformance Tests / client-conformance (push) Failing after 3s
Conformance Tests / server-conformance (push) Failing after 1s
GitHub Actions Security Analysis / zizmor (push) Failing after 1s
CI / checks (push) Failing after 59m20s
CI / all-green (push) Has been cancelled
chore: import upstream snapshot with attribution
2026-07-13 12:10:27 +08:00

383 lines
16 KiB
Python

"""Tests for `Connection`.
`Connection` wraps an `Outbound` (the standalone stream). Construct it via the
`from_envelope` / `for_loop` factories so `protocol_version` is always
populated and `has_standalone_channel` is derived from the held outbound. Its
`notify` is best-effort (never raises); `send_raw_request` raises
`NoBackChannelError` structurally from the no-channel sentinel. Tested with a
stub `Outbound` so we can assert wire shape and inject failures.
"""
import logging
from collections.abc import Mapping
from typing import Any, Literal
import anyio
import pytest
from mcp_types import (
LATEST_PROTOCOL_VERSION,
ClientCapabilities,
CreateMessageRequest,
CreateMessageRequestParams,
ElicitationCapability,
EmptyResult,
Implementation,
ListRootsRequest,
ListRootsResult,
PingRequest,
Request,
RequestParams,
RootsCapability,
SamplingCapability,
SamplingContextCapability,
SamplingToolsCapability,
)
from mcp_types.version import LATEST_HANDSHAKE_VERSION, LATEST_MODERN_VERSION
from pydantic import BaseModel, ValidationError
from mcp.server.connection import Connection
from mcp.shared.dispatcher import CallOptions
from mcp.shared.exceptions import NoBackChannelError
_CLIENT_INFO = Implementation(name="t", version="0")
class StubOutbound:
def __init__(
self, *, result: dict[str, Any] | None = None, raise_on_send: type[BaseException] | None = None
) -> None:
self.requests: list[tuple[str, Mapping[str, Any] | None]] = []
self.notifications: list[tuple[str, Mapping[str, Any] | None]] = []
self._result = result if result is not None else {}
self._raise_on_send = raise_on_send
async def send_raw_request(
self, method: str, params: Mapping[str, Any] | None, opts: CallOptions | None = None
) -> dict[str, Any]:
self.requests.append((method, params))
return self._result
async def notify(self, method: str, params: Mapping[str, Any] | None, opts: CallOptions | None = None) -> None:
if self._raise_on_send is not None:
raise self._raise_on_send()
self.notifications.append((method, params))
# --- factories -----------------------------------------------------------------
def test_from_envelope_is_born_ready_with_no_back_channel():
"""SDK-defined: `from_envelope` populates `protocol_version`, sets `initialized`,
and holds the no-channel sentinel so `has_standalone_channel` derives False."""
conn = Connection.from_envelope(LATEST_MODERN_VERSION, None, None)
assert conn.protocol_version == LATEST_MODERN_VERSION
assert conn.initialized.is_set()
assert conn.initialize_accepted is True
assert conn.has_standalone_channel is False
assert conn.client_params is None
assert conn.session_id is None
def test_from_envelope_records_client_params_when_both_info_and_caps_supplied():
"""SDK-defined: when both client info and capabilities are supplied,
`from_envelope` synthesizes `client_params` so capability checks can run."""
caps = ClientCapabilities(sampling=SamplingCapability())
conn = Connection.from_envelope(LATEST_MODERN_VERSION, _CLIENT_INFO, caps)
assert conn.client_params is not None
assert conn.client_params.client_info.name == "t"
assert conn.client_params.capabilities.sampling is not None
assert conn.client_params.protocol_version == LATEST_MODERN_VERSION
@pytest.mark.parametrize(
("info", "caps"),
[(None, ClientCapabilities()), (_CLIENT_INFO, None)],
)
def test_from_envelope_leaves_client_params_none_when_either_is_missing(
info: Implementation | None, caps: ClientCapabilities | None
):
"""SDK-defined: `client_params` is only synthesized when both info and
caps are present; either missing leaves it `None`."""
conn = Connection.from_envelope(LATEST_MODERN_VERSION, info, caps)
assert conn.client_params is None
def test_from_envelope_with_explicit_outbound_has_standalone_channel():
"""SDK-defined: duplex modern transports pass an outbound; `has_standalone_channel`
derives True since the held outbound is not the no-channel sentinel."""
out = StubOutbound()
conn = Connection.from_envelope(LATEST_MODERN_VERSION, None, None, outbound=out)
assert conn.has_standalone_channel is True
assert conn.outbound is out
assert conn.initialized.is_set()
def test_for_loop_seeds_version_from_hint_or_latest_and_is_not_born_ready():
"""SDK-defined: `for_loop` seeds `protocol_version` from the hint when given,
else `LATEST_HANDSHAKE_VERSION`; the connection awaits the initialize handshake."""
out = StubOutbound()
conn = Connection.for_loop(out)
assert conn.protocol_version == LATEST_HANDSHAKE_VERSION
assert conn.has_standalone_channel is True
assert not conn.initialized.is_set()
assert conn.initialize_accepted is False
assert conn.client_params is None
hinted = Connection.for_loop(out, protocol_version_hint=LATEST_MODERN_VERSION)
assert hinted.protocol_version == LATEST_MODERN_VERSION
def test_for_loop_records_session_id_when_supplied():
"""SDK-defined: `for_loop` stores the `session_id` kwarg verbatim."""
conn = Connection.for_loop(StubOutbound(), session_id="sess-1")
assert conn.session_id == "sess-1"
# --- outbound channel ----------------------------------------------------------
@pytest.mark.anyio
async def test_connection_notify_forwards_to_outbound():
out = StubOutbound()
conn = Connection.for_loop(out)
await conn.notify("notifications/message", {"level": "info", "data": "hi"})
assert out.notifications == [("notifications/message", {"level": "info", "data": "hi"})]
@pytest.mark.anyio
async def test_connection_notify_swallows_broken_stream_and_debug_logs(caplog: pytest.LogCaptureFixture):
caplog.set_level(logging.DEBUG, logger="mcp.server.connection")
out = StubOutbound(raise_on_send=anyio.BrokenResourceError)
conn = Connection.for_loop(out)
await conn.notify("notifications/message", {"data": "x"}) # must not raise
assert "stream closed" in caplog.text.lower()
@pytest.mark.anyio
async def test_connection_notify_drops_when_no_standalone_channel(caplog: pytest.LogCaptureFixture):
"""SDK-defined: the no-channel sentinel debug-logs and drops; `notify` never raises."""
caplog.set_level(logging.DEBUG, logger="mcp.server.connection")
conn = Connection.from_envelope(LATEST_PROTOCOL_VERSION, None, None)
await conn.notify("notifications/message", {"data": "x"}) # must not raise
assert "no standalone channel" in caplog.text.lower()
@pytest.mark.anyio
async def test_connection_send_raw_request_raises_nobackchannel_when_no_standalone_channel():
"""SDK-defined: the no-channel sentinel raises structurally; `Connection` does no pre-check."""
conn = Connection.from_envelope(LATEST_PROTOCOL_VERSION, None, None)
with pytest.raises(NoBackChannelError):
await conn.send_raw_request("ping", None)
@pytest.mark.anyio
async def test_connection_send_raw_request_forwards_when_standalone_channel_present():
out = StubOutbound()
conn = Connection.for_loop(out)
result = await conn.send_raw_request("ping", None)
assert out.requests == [("ping", None)]
assert result == {}
@pytest.mark.anyio
async def test_connection_send_request_with_spec_type_infers_result_type():
out = StubOutbound(result={"roots": [{"uri": "file:///ws"}]})
conn = Connection.for_loop(out)
result = await conn.send_request(ListRootsRequest())
method, _ = out.requests[0]
assert method == "roots/list"
assert isinstance(result, ListRootsResult)
assert str(result.roots[0].uri) == "file:///ws"
@pytest.mark.anyio
async def test_connection_send_request_validates_result_alias_only():
"""Peer results validate alias-only; a snake_case key from the wire is
ignored as extra, not populated by Python field name."""
snake = {"role": "assistant", "content": {"type": "text", "text": "x"}, "model": "m", "stop_reason": "endTurn"}
conn = Connection.for_loop(StubOutbound(result=snake))
result = await conn.send_request(CreateMessageRequest(params=CreateMessageRequestParams(messages=[], max_tokens=1)))
assert result.stop_reason is None
@pytest.mark.anyio
async def test_connection_send_request_with_result_type_kwarg_validates_custom_type():
out = StubOutbound(result={})
conn = Connection.for_loop(out)
result = await conn.send_request(PingRequest(), result_type=EmptyResult)
assert isinstance(result, EmptyResult)
@pytest.mark.anyio
async def test_connection_send_request_nonconforming_result_raises_validation_error():
conn = Connection.for_loop(StubOutbound(result={"bogus": 1}))
with pytest.raises(ValidationError):
await conn.send_request(ListRootsRequest())
@pytest.mark.anyio
async def test_send_request_validates_the_client_result_against_the_surface_schema():
"""A spec-method result that fails the per-version surface schema raises
`ValidationError` even when the caller's `result_type` would accept it."""
conn = Connection.for_loop(StubOutbound(result={"roots": "nope"}))
with pytest.raises(ValidationError):
await conn.send_request(ListRootsRequest(), result_type=EmptyResult)
@pytest.mark.anyio
async def test_send_request_passes_a_spec_valid_client_result():
"""A spec-valid client result passes the surface gate and parses to the typed model."""
conn = Connection.for_loop(StubOutbound(result={"roots": [{"uri": "file:///ws"}]}))
assert conn.protocol_version == LATEST_HANDSHAKE_VERSION
result = await conn.send_request(ListRootsRequest())
assert isinstance(result, ListRootsResult)
assert str(result.roots[0].uri) == "file:///ws"
class _CustomRequest(Request[RequestParams | None, Literal["custom/echo"]]):
method: Literal["custom/echo"] = "custom/echo"
params: RequestParams | None = None
class _CustomResult(BaseModel):
value: int
@pytest.mark.anyio
async def test_send_request_skips_the_surface_gate_when_method_absent_at_version():
"""Surface row absent for the negotiated version: gate is bypassed and only
the inferred result type validates."""
conn = Connection.for_loop(StubOutbound(result={}), protocol_version_hint=LATEST_MODERN_VERSION)
result = await conn.send_request(PingRequest())
assert isinstance(result, EmptyResult)
@pytest.mark.anyio
async def test_send_request_with_a_custom_method_skips_the_surface_gate():
"""Non-spec methods are not blocked by the surface gate; `result_type` validates."""
conn = Connection.for_loop(StubOutbound(result={"value": 7}))
result = await conn.send_request(_CustomRequest(), result_type=_CustomResult)
assert isinstance(result, _CustomResult)
assert result.value == 7
@pytest.mark.anyio
async def test_connection_ping_sends_ping_on_standalone():
out = StubOutbound()
conn = Connection.for_loop(out)
await conn.ping()
assert out.requests == [("ping", None)]
@pytest.mark.anyio
async def test_connection_log_sends_logging_message_notification():
out = StubOutbound()
conn = Connection.for_loop(out)
await conn.log("info", {"k": "v"}, logger="my.logger") # pyright: ignore[reportDeprecated]
method, params = out.notifications[0]
assert method == "notifications/message"
assert params is not None
assert params["level"] == "info"
assert params["data"] == {"k": "v"}
assert params["logger"] == "my.logger"
@pytest.mark.anyio
async def test_connection_log_with_meta_includes_meta_in_params():
out = StubOutbound()
conn = Connection.for_loop(out)
await conn.log("info", "x", meta={"traceId": "abc"}) # pyright: ignore[reportDeprecated]
_, params = out.notifications[0]
assert params is not None
assert params["_meta"] == {"traceId": "abc"}
@pytest.mark.anyio
async def test_connection_list_changed_notifications_send_correct_methods():
out = StubOutbound()
conn = Connection.for_loop(out)
await conn.send_tool_list_changed()
await conn.send_prompt_list_changed()
await conn.send_resource_list_changed()
await conn.send_resource_updated("file:///workspace/a.txt")
methods = [m for m, _ in out.notifications]
assert methods == [
"notifications/tools/list_changed",
"notifications/prompts/list_changed",
"notifications/resources/list_changed",
"notifications/resources/updated",
]
assert out.notifications[-1][1] == {"uri": "file:///workspace/a.txt"}
@pytest.mark.anyio
async def test_connection_send_tool_list_changed_with_meta_includes_meta_only_params():
out = StubOutbound()
conn = Connection.for_loop(out)
await conn.send_tool_list_changed(meta={"k": 1})
assert out.notifications == [("notifications/tools/list_changed", {"_meta": {"k": 1}})]
# --- check_capability ----------------------------------------------------------
def test_connection_check_capability_false_when_no_client_params_recorded():
"""SDK-defined: `check_capability` returns False when no `client_params`
were recorded, regardless of which factory built the connection."""
conn = Connection.for_loop(StubOutbound())
assert conn.check_capability(ClientCapabilities(sampling=SamplingCapability())) is False
# Same for a born-ready connection that supplied neither info nor caps.
assert Connection.from_envelope(LATEST_MODERN_VERSION, None, None).check_capability(ClientCapabilities()) is False
@pytest.mark.parametrize(
("have", "want", "expected"),
[
(ClientCapabilities(roots=None), ClientCapabilities(roots=RootsCapability()), False),
(
ClientCapabilities(roots=RootsCapability(list_changed=False)),
ClientCapabilities(roots=RootsCapability(list_changed=True)),
False,
),
(ClientCapabilities(sampling=None), ClientCapabilities(sampling=SamplingCapability()), False),
(
ClientCapabilities(sampling=SamplingCapability()),
ClientCapabilities(sampling=SamplingCapability(context=SamplingContextCapability())),
False,
),
(
ClientCapabilities(sampling=SamplingCapability()),
ClientCapabilities(sampling=SamplingCapability(tools=SamplingToolsCapability())),
False,
),
(
ClientCapabilities(sampling=SamplingCapability(tools=SamplingToolsCapability())),
ClientCapabilities(sampling=SamplingCapability(tools=SamplingToolsCapability())),
True,
),
(
ClientCapabilities(sampling=SamplingCapability(context=SamplingContextCapability())),
ClientCapabilities(sampling=SamplingCapability(context=SamplingContextCapability())),
True,
),
(ClientCapabilities(experimental=None), ClientCapabilities(experimental={"a": {}}), False),
(ClientCapabilities(experimental={"a": {}}), ClientCapabilities(experimental={"b": {}}), False),
(ClientCapabilities(experimental={"a": {"x": 1}}), ClientCapabilities(experimental={"a": {"x": 2}}), False),
(ClientCapabilities(experimental={"a": {}}), ClientCapabilities(experimental={"a": {}}), True),
],
)
def test_check_capability_per_field_branches(have: ClientCapabilities, want: ClientCapabilities, expected: bool):
conn = Connection.from_envelope(LATEST_PROTOCOL_VERSION, _CLIENT_INFO, have)
assert conn.check_capability(want) is expected
def test_connection_check_capability_true_when_client_declares_it():
conn = Connection.from_envelope(
LATEST_PROTOCOL_VERSION,
_CLIENT_INFO,
ClientCapabilities(sampling=SamplingCapability(), roots=RootsCapability(list_changed=True)),
)
assert conn.check_capability(ClientCapabilities(sampling=SamplingCapability())) is True
assert conn.check_capability(ClientCapabilities(roots=RootsCapability(list_changed=True))) is True
assert conn.check_capability(ClientCapabilities(elicitation=ElicitationCapability())) is False