Files
modelcontextprotocol--pytho…/tests/server/test_session.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) Waiting to run
chore: import upstream snapshot with attribution
2026-07-13 12:10:27 +08:00

257 lines
11 KiB
Python

"""Tests for `ServerSession`.
`ServerSession` is a thin per-request proxy over two `Outbound` channels and a
`Connection`. Tested with stub outbounds so we can assert what reaches the wire
(method, params, `CallOptions`) and which channel it routed to, without standing
up a transport.
"""
from collections.abc import Mapping
from typing import Any
import mcp_types as types
import pytest
from mcp_types import (
ClientCapabilities,
Implementation,
SamplingCapability,
SamplingToolsCapability,
)
from mcp_types.version import LATEST_HANDSHAKE_VERSION, LATEST_MODERN_VERSION
from pydantic import ValidationError
from mcp.server.connection import Connection
from mcp.server.session import ServerSession
from mcp.shared.dispatcher import CallOptions
from mcp.shared.message import ServerMessageMetadata
class StubOutbound:
"""Records `send_raw_request` / `notify` / `progress` calls and returns a canned result.
Structurally a `DispatchContext[Any]` so it can stand in for the per-request channel.
"""
transport: Any = None
can_send_request: bool = True
request_id: Any = None
message_metadata: Any = None
cancel_requested: Any = None
def __init__(self, result: dict[str, Any] | None = None) -> None:
self.requests: list[tuple[str, Mapping[str, Any] | None, CallOptions | None]] = []
self.notifications: list[tuple[str, Mapping[str, Any] | None]] = []
self.progress_calls: list[tuple[float, float | None, str | None]] = []
self.result = result if result is not None else {}
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, opts))
return self.result
async def notify(self, method: str, params: Mapping[str, Any] | None, opts: CallOptions | None = None) -> None:
self.notifications.append((method, params))
async def progress(self, progress: float, total: float | None = None, message: str | None = None) -> None:
self.progress_calls.append((progress, total, message))
def _make_session(
outbound: StubOutbound,
*,
capabilities: ClientCapabilities | None = None,
protocol_version: str = LATEST_HANDSHAKE_VERSION,
) -> ServerSession:
"""Single-channel session: the stub is both request and standalone outbound."""
client_info = Implementation(name="c", version="0") if capabilities is not None else None
conn = Connection.from_envelope(protocol_version, client_info, capabilities, outbound=outbound)
return ServerSession(outbound, conn)
def _two_channel_session(request_ch: StubOutbound, standalone_ch: StubOutbound) -> ServerSession:
"""Distinct request/standalone outbounds so routing assertions can tell the channels apart."""
conn = Connection.from_envelope(LATEST_HANDSHAKE_VERSION, None, None, outbound=standalone_ch)
return ServerSession(request_ch, conn)
@pytest.mark.anyio
async def test_send_request_forwards_timeout_and_progress_callback_as_call_options():
outbound = StubOutbound(result={"roots": []})
session = _make_session(outbound)
async def on_progress(progress: float, total: float | None, message: str | None) -> None:
raise NotImplementedError
result = await session.send_request(
types.ListRootsRequest(),
types.ListRootsResult,
request_read_timeout_seconds=2.5,
progress_callback=on_progress,
)
assert isinstance(result, types.ListRootsResult)
method, _params, opts = outbound.requests[0]
assert method == "roots/list"
assert opts == {"timeout": 2.5, "on_progress": on_progress}
@pytest.mark.anyio
async def test_send_request_omits_call_options_when_none_given():
outbound = StubOutbound(result={"roots": []})
session = _make_session(outbound)
await session.send_request(types.ListRootsRequest(), types.ListRootsResult)
_method, _params, opts = outbound.requests[0]
assert opts is None
@pytest.mark.anyio
async def test_send_request_timeout_zero_is_forwarded():
"""0 is a real timeout (fail at the first checkpoint, `anyio.fail_after(0)`
semantics) and must reach the channel; only `None` means "no timeout"."""
outbound = StubOutbound(result={})
session = _make_session(outbound)
await session.send_request(types.PingRequest(), types.EmptyResult, request_read_timeout_seconds=0.0)
assert outbound.requests[0][2] == {"timeout": 0.0}
@pytest.mark.anyio
async def test_send_request_without_related_id_routes_to_standalone_channel():
"""SDK-defined: no `related_request_id` routes the request onto the connection's standalone channel."""
request_ch = StubOutbound()
standalone_ch = StubOutbound(result={"roots": []})
session = _two_channel_session(request_ch, standalone_ch)
await session.send_request(types.ListRootsRequest(), types.ListRootsResult)
assert request_ch.requests == []
assert standalone_ch.requests[0][0] == "roots/list"
@pytest.mark.anyio
async def test_send_request_with_related_id_routes_to_request_channel():
"""SDK-defined: with `related_request_id` the request rides the per-request channel
(the originating POST's response stream over streamable HTTP)."""
request_ch = StubOutbound(result={"action": "cancel"})
standalone_ch = StubOutbound()
session = _two_channel_session(request_ch, standalone_ch)
result = await session.send_request(
types.ElicitRequest(params=types.ElicitRequestFormParams(message="q", requested_schema={})),
types.ElicitResult,
metadata=ServerMessageMetadata(related_request_id=7),
)
assert isinstance(result, types.ElicitResult)
assert standalone_ch.requests == []
assert request_ch.requests[0][0] == "elicitation/create"
@pytest.mark.anyio
async def test_send_notification_routes_by_related_request_id():
"""SDK-defined: notifications select channel by `related_request_id` exactly like requests."""
request_ch = StubOutbound()
standalone_ch = StubOutbound()
session = _two_channel_session(request_ch, standalone_ch)
await session.send_tool_list_changed()
await session.send_progress_notification("tok", 0.5, related_request_id="req-1")
assert [m for m, _ in standalone_ch.notifications] == ["notifications/tools/list_changed"]
assert [m for m, _ in request_ch.notifications] == ["notifications/progress"]
@pytest.mark.anyio
async def test_report_progress_delegates_to_the_request_dispatch_context():
"""`report_progress` calls the per-request `DispatchContext.progress` seam, never the
standalone channel: token gating and routing live in the dispatcher, not here."""
request_ch = StubOutbound()
standalone_ch = StubOutbound()
session = _two_channel_session(request_ch, standalone_ch)
await session.report_progress(0.5, total=1.0, message="halfway")
assert request_ch.progress_calls == [(0.5, 1.0, "halfway")]
assert standalone_ch.progress_calls == []
assert request_ch.notifications == []
@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."""
session = _make_session(StubOutbound(result={"roots": "nope"}))
with pytest.raises(ValidationError):
await session.send_request(types.ListRootsRequest(), types.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."""
session = _make_session(StubOutbound(result={"roots": [{"uri": "file:///ws"}]}))
result = await session.send_request(types.ListRootsRequest(), types.ListRootsResult)
assert isinstance(result, types.ListRootsResult)
assert str(result.roots[0].uri) == "file:///ws"
@pytest.mark.anyio
async def test_send_request_skips_the_surface_gate_when_method_absent_at_version():
"""Surface row absent for the connection's version: gate is bypassed and only
`result_type` validates."""
session = _make_session(StubOutbound(result={}), protocol_version=LATEST_MODERN_VERSION)
result = await session.send_request(types.PingRequest(), types.EmptyResult)
assert isinstance(result, types.EmptyResult)
@pytest.mark.anyio
async def test_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"}
session = _make_session(StubOutbound(result=snake))
request = types.CreateMessageRequest(params=types.CreateMessageRequestParams(messages=[], max_tokens=1))
result = await session.send_request(request, types.CreateMessageResult)
assert result.stop_reason is None
@pytest.mark.anyio
async def test_create_message_with_tools_returns_with_tools_result():
outbound = StubOutbound(result={"role": "assistant", "content": [{"type": "text", "text": "ok"}], "model": "m"})
session = _make_session(
outbound, capabilities=ClientCapabilities(sampling=SamplingCapability(tools=SamplingToolsCapability()))
)
result = await session.create_message( # pyright: ignore[reportDeprecated]
messages=[types.SamplingMessage(role="user", content=types.TextContent(type="text", text="hi"))],
max_tokens=10,
tools=[types.Tool(name="t", input_schema={"type": "object"})],
)
assert isinstance(result, types.CreateMessageResultWithTools)
method, params, _opts = outbound.requests[0]
assert method == "sampling/createMessage"
assert params is not None and params["tools"][0]["name"] == "t"
@pytest.mark.anyio
async def test_create_message_with_tool_choice_only_returns_with_tools_result():
# tool_choice alone is tools-mode: the answer may carry array content.
outbound = StubOutbound(result={"role": "assistant", "content": [{"type": "text", "text": "ok"}], "model": "m"})
session = _make_session(
outbound, capabilities=ClientCapabilities(sampling=SamplingCapability(tools=SamplingToolsCapability()))
)
result = await session.create_message( # pyright: ignore[reportDeprecated]
messages=[types.SamplingMessage(role="user", content=types.TextContent(type="text", text="hi"))],
max_tokens=10,
tool_choice=types.ToolChoice(mode="none"),
)
assert isinstance(result, types.CreateMessageResultWithTools)
def test_check_client_capability_delegates_to_connection():
outbound = StubOutbound()
session = _make_session(outbound, capabilities=ClientCapabilities(sampling=SamplingCapability()))
assert session.check_client_capability(ClientCapabilities(sampling=SamplingCapability())) is True
assert session.check_client_capability(ClientCapabilities(experimental={"x": {}})) is False
def test_protocol_version_proxies_connection():
"""SDK-defined: `session.protocol_version` reads through to the held `Connection`."""
_ARBITRARY_VERSION = "sentinel-version" # identity-only: any string the connection holds
conn = Connection.from_envelope(_ARBITRARY_VERSION, None, None)
session = ServerSession(StubOutbound(), conn)
assert session.protocol_version == _ARBITRARY_VERSION
assert session.client_params is None