fastmcp/tests/server/test_context.py
2026-01-12 15:33:59 -05:00

293 lines
10 KiB
Python

from unittest.mock import MagicMock
import pytest
from mcp.types import ModelPreferences
from fastmcp.server.context import (
Context,
_parse_model_preferences,
reset_transport,
set_transport,
)
from fastmcp.server.server import FastMCP
@pytest.fixture
def context():
return Context(fastmcp=FastMCP())
class TestParseModelPreferences:
def test_parse_model_preferences_string(self, context):
mp = _parse_model_preferences("claude-haiku-4-5")
assert isinstance(mp, ModelPreferences)
assert mp.hints is not None
assert mp.hints[0].name == "claude-haiku-4-5"
def test_parse_model_preferences_list(self, context):
mp = _parse_model_preferences(["claude-haiku-4-5", "claude"])
assert isinstance(mp, ModelPreferences)
assert mp.hints is not None
assert [h.name for h in mp.hints] == ["claude-haiku-4-5", "claude"]
def test_parse_model_preferences_object(self, context):
obj = ModelPreferences(hints=[])
assert _parse_model_preferences(obj) is obj
def test_parse_model_preferences_invalid_type(self, context):
with pytest.raises(ValueError):
_parse_model_preferences(model_preferences=123) # pyright: ignore[reportArgumentType] # type: ignore[invalid-argument-type]
class TestSessionId:
def test_session_id_with_http_headers(self, context):
"""Test that session_id returns the value from mcp-session-id header."""
from mcp.server.lowlevel.server import request_ctx
from mcp.shared.context import RequestContext
mock_headers = {"mcp-session-id": "test-session-123"}
token = request_ctx.set(
RequestContext( # type: ignore[arg-type]
request_id=0,
meta=None,
session=MagicMock(wraps={}),
lifespan_context=MagicMock(),
request=MagicMock(headers=mock_headers),
)
)
assert context.session_id == "test-session-123"
request_ctx.reset(token)
def test_session_id_without_http_headers(self, context):
"""Test that session_id returns a UUID string when no HTTP headers are available."""
import uuid
from mcp.server.lowlevel.server import request_ctx
from mcp.shared.context import RequestContext
token = request_ctx.set(
RequestContext( # type: ignore[arg-type]
request_id=0,
meta=None,
session=MagicMock(wraps={}),
lifespan_context=MagicMock(),
)
)
assert uuid.UUID(context.session_id)
request_ctx.reset(token)
class TestContextState:
"""Test suite for Context state functionality."""
async def test_context_state(self):
"""Test that state modifications in child contexts don't affect parent."""
mock_fastmcp = MagicMock()
async with Context(fastmcp=mock_fastmcp) as context:
assert context.get_state("test1") is None
assert context.get_state("test2") is None
context.set_state("test1", "value")
context.set_state("test2", 2)
assert context.get_state("test1") == "value"
assert context.get_state("test2") == 2
context.set_state("test1", "new_value")
assert context.get_state("test1") == "new_value"
async def test_context_state_inheritance(self):
"""Test that child contexts inherit parent state."""
mock_fastmcp = MagicMock()
async with Context(fastmcp=mock_fastmcp) as context1:
context1.set_state("key1", "key1-context1")
context1.set_state("key2", "key2-context1")
async with Context(fastmcp=mock_fastmcp) as context2:
# Override one key
context2.set_state("key1", "key1-context2")
assert context2.get_state("key1") == "key1-context2"
assert context1.get_state("key1") == "key1-context1"
assert context2.get_state("key2") == "key2-context1"
async with Context(fastmcp=mock_fastmcp) as context3:
# Verify state was inherited
assert context3.get_state("key1") == "key1-context2"
assert context3.get_state("key2") == "key2-context1"
# Add a new key and verify parents were not affected
context3.set_state("key-context3-only", 1)
assert context1.get_state("key-context3-only") is None
assert context2.get_state("key-context3-only") is None
assert context3.get_state("key-context3-only") == 1
assert context1.get_state("key1") == "key1-context1"
assert context1.get_state("key-context3-only") is None
class TestContextMeta:
"""Test suite for Context meta functionality."""
def test_request_context_meta_access(self, context):
"""Test that meta can be accessed from request context."""
from mcp.server.lowlevel.server import request_ctx
from mcp.shared.context import RequestContext
# Create a mock meta object with attributes
class MockMeta:
def __init__(self):
self.user_id = "user-123"
self.trace_id = "trace-456"
self.custom_field = "custom-value"
mock_meta = MockMeta()
token = request_ctx.set(
RequestContext( # type: ignore[arg-type]
request_id=0,
meta=mock_meta, # type: ignore[arg-type]
session=MagicMock(wraps={}),
lifespan_context=MagicMock(),
)
)
# Access meta through context
retrieved_meta = context.request_context.meta
assert retrieved_meta is not None
assert retrieved_meta.user_id == "user-123"
assert retrieved_meta.trace_id == "trace-456"
assert retrieved_meta.custom_field == "custom-value"
request_ctx.reset(token)
def test_request_context_meta_none(self, context):
"""Test that context handles None meta gracefully."""
from mcp.server.lowlevel.server import request_ctx
from mcp.shared.context import RequestContext
token = request_ctx.set(
RequestContext( # type: ignore[arg-type]
request_id=0,
meta=None,
session=MagicMock(wraps={}),
lifespan_context=MagicMock(),
)
)
# Access meta through context
retrieved_meta = context.request_context.meta
assert retrieved_meta is None
request_ctx.reset(token)
class TestTransport:
"""Test suite for Context transport property."""
def test_transport_returns_none_outside_server_context(self, context):
"""Test that transport returns None when not in a server context."""
assert context.transport is None
def test_transport_returns_stdio(self, context):
"""Test that transport returns 'stdio' when set."""
token = set_transport("stdio")
try:
assert context.transport == "stdio"
finally:
reset_transport(token)
def test_transport_returns_sse(self, context):
"""Test that transport returns 'sse' when set."""
token = set_transport("sse")
try:
assert context.transport == "sse"
finally:
reset_transport(token)
def test_transport_returns_streamable_http(self, context):
"""Test that transport returns 'streamable-http' when set."""
token = set_transport("streamable-http")
try:
assert context.transport == "streamable-http"
finally:
reset_transport(token)
def test_transport_reset(self, context):
"""Test that transport resets correctly."""
assert context.transport is None
token = set_transport("stdio")
assert context.transport == "stdio"
reset_transport(token)
assert context.transport is None
class TestTransportIntegration:
"""Integration tests for transport property with actual server/client."""
async def test_transport_in_tool_via_client(self):
"""Test that transport is accessible from within a tool via Client."""
from fastmcp import Client
mcp = FastMCP("test")
observed_transport = None
@mcp.tool
def get_transport(ctx: Context) -> str:
nonlocal observed_transport
observed_transport = ctx.transport
return observed_transport or "none"
# Client uses in-memory transport which doesn't set transport type
# so we expect None here (the transport is only set by run_* methods)
async with Client(mcp) as client:
result = await client.call_tool("get_transport", {})
assert observed_transport is None
assert result.data == "none"
async def test_transport_set_manually_is_visible_in_tool(self):
"""Test that manually set transport is visible from within a tool."""
from fastmcp import Client
mcp = FastMCP("test")
observed_transport = None
@mcp.tool
def get_transport(ctx: Context) -> str:
nonlocal observed_transport
observed_transport = ctx.transport
return observed_transport or "none"
# Manually set transport before running
token = set_transport("stdio")
try:
async with Client(mcp) as client:
result = await client.call_tool("get_transport", {})
assert observed_transport == "stdio"
assert result.data == "stdio"
finally:
reset_transport(token)
async def test_transport_set_via_http_middleware(self):
"""Test that transport is set per-request via HTTP middleware."""
from fastmcp import Client
from fastmcp.client.transports import StreamableHttpTransport
from fastmcp.utilities.tests import run_server_async
mcp = FastMCP("test")
observed_transport = None
@mcp.tool
def get_transport(ctx: Context) -> str:
nonlocal observed_transport
observed_transport = ctx.transport
return observed_transport or "none"
async with run_server_async(mcp, transport="streamable-http") as url:
transport = StreamableHttpTransport(url=url)
async with Client(transport=transport) as client:
result = await client.call_tool("get_transport", {})
assert observed_transport == "streamable-http"
assert result.data == "streamable-http"