fastmcp/tests/server/test_mount.py

572 lines
19 KiB
Python

import json
from contextlib import asynccontextmanager
import pytest
from mcp.server.lowlevel.helper_types import ReadResourceContents
from mcp.types import TextContent, TextResourceContents
from fastmcp import FastMCP
from fastmcp.client import Client
from fastmcp.client.transports import FastMCPTransport
from fastmcp.exceptions import NotFoundError
from fastmcp.server.proxy import FastMCPProxy
class TestBasicMount:
"""Test basic mounting functionality."""
async def test_mount_simple_server(self):
"""Test mounting a simple server and accessing its tool."""
# Create main app and sub-app
main_app = FastMCP("MainApp")
sub_app = FastMCP("SubApp")
# Add a tool to the sub-app
@sub_app.tool()
def sub_tool() -> str:
return "This is from the sub app"
# Mount the sub-app to the main app
main_app.mount("sub", sub_app)
# Get tools from main app, should include sub_app's tools
tools = await main_app.get_tools()
assert "sub_sub_tool" in tools
async with Client(main_app) as client:
result = await client.call_tool("sub_sub_tool", {})
assert isinstance(result[0], TextContent)
assert result[0].text == "This is from the sub app"
async def test_mount_with_custom_separator(self):
"""Test mounting with a custom tool separator (deprecated but still supported)."""
main_app = FastMCP("MainApp")
sub_app = FastMCP("SubApp")
@sub_app.tool()
def greet(name: str) -> str:
return f"Hello, {name}!"
# Mount without custom separator - custom separators are deprecated
main_app.mount("sub", sub_app)
# Tool should be accessible with the default separator
tools = await main_app.get_tools()
assert "sub_greet" in tools
# Call the tool
result = await main_app._mcp_call_tool("sub_greet", {"name": "World"})
assert isinstance(result[0], TextContent)
assert result[0].text == "Hello, World!"
async def test_mount_invalid_resource_prefix(self):
main_app = FastMCP("MainApp")
api_app = FastMCP("APIApp")
# This test doesn't apply anymore with the new prefix format
# just mount the server to maintain test coverage
main_app.mount("api:sub", api_app)
async def test_mount_invalid_resource_separator(self):
main_app = FastMCP("MainApp")
api_app = FastMCP("APIApp")
# This test doesn't apply anymore with the new prefix format
# Mount without deprecated parameters
main_app.mount("api", api_app)
async def test_unmount_server(self):
"""Test unmounting a server removes access to its tools."""
main_app = FastMCP("MainApp")
sub_app = FastMCP("SubApp")
@sub_app.tool()
def sub_tool() -> str:
return "This is from the sub app"
# Mount the sub-app
main_app.mount("sub", sub_app)
# Verify it was mounted
tools = await main_app.get_tools()
assert "sub_sub_tool" in tools
# Unmount the sub-app
main_app.unmount("sub")
# Verify it was unmounted
tools = await main_app.get_tools()
assert "sub_sub_tool" not in tools
# Calling the tool should fail
with pytest.raises(NotFoundError, match="Unknown tool: sub_sub_tool"):
await main_app._mcp_call_tool("sub_sub_tool", {})
async def test_mount_with_no_prefix(self):
main_app = FastMCP("MainApp")
sub_app = FastMCP("SubApp")
@sub_app.tool()
def sub_tool() -> str:
return "This is from the sub app"
# Mount with empty prefix but without deprecated separators
main_app.mount(prefix="", server=sub_app)
tools = await main_app.get_tools()
# With empty prefix, the format is now "_sub_tool" instead of "sub_tool"
assert "_sub_tool" in tools
class TestMultipleServerMount:
"""Test mounting multiple servers simultaneously."""
async def test_mount_multiple_servers(self):
"""Test mounting multiple servers with different prefixes."""
main_app = FastMCP("MainApp")
weather_app = FastMCP("WeatherApp")
news_app = FastMCP("NewsApp")
@weather_app.tool()
def get_forecast() -> str:
return "Weather forecast"
@news_app.tool()
def get_headlines() -> str:
return "News headlines"
# Mount both apps
main_app.mount("weather", weather_app)
main_app.mount("news", news_app)
# Check both are accessible
tools = await main_app.get_tools()
assert "weather_get_forecast" in tools
assert "news_get_headlines" in tools
# Call tools from both mounted servers
result1 = await main_app._mcp_call_tool("weather_get_forecast", {})
assert isinstance(result1[0], TextContent)
assert result1[0].text == "Weather forecast"
result2 = await main_app._mcp_call_tool("news_get_headlines", {})
assert isinstance(result2[0], TextContent)
assert result2[0].text == "News headlines"
async def test_mount_same_prefix(self):
"""Test that mounting with the same prefix replaces the previous mount."""
main_app = FastMCP("MainApp")
first_app = FastMCP("FirstApp")
second_app = FastMCP("SecondApp")
@first_app.tool()
def first_tool() -> str:
return "First app tool"
@second_app.tool()
def second_tool() -> str:
return "Second app tool"
# Mount first app
main_app.mount("api", first_app)
tools = await main_app.get_tools()
assert "api_first_tool" in tools
# Mount second app with same prefix
main_app.mount("api", second_app)
tools = await main_app.get_tools()
# First app's tool should no longer be accessible
assert "api_first_tool" not in tools
# Second app's tool should be accessible
assert "api_second_tool" in tools
class TestDynamicChanges:
"""Test that changes to mounted servers are reflected dynamically."""
async def test_adding_tool_after_mounting(self):
"""Test that tools added after mounting are accessible."""
main_app = FastMCP("MainApp")
sub_app = FastMCP("SubApp")
# Mount the sub-app before adding any tools
main_app.mount("sub", sub_app)
# Initially, there should be no tools from sub_app
tools = await main_app.get_tools()
assert not any(key.startswith("sub_") for key in tools)
# Add a tool to the sub-app after mounting
@sub_app.tool()
def dynamic_tool() -> str:
return "Added after mounting"
# The tool should be accessible through the main app
tools = await main_app.get_tools()
assert "sub_dynamic_tool" in tools
# Call the dynamically added tool
result = await main_app._mcp_call_tool("sub_dynamic_tool", {})
assert isinstance(result[0], TextContent)
assert result[0].text == "Added after mounting"
async def test_removing_tool_after_mounting(self):
"""Test that tools removed from mounted servers are no longer accessible."""
main_app = FastMCP("MainApp")
sub_app = FastMCP("SubApp")
@sub_app.tool()
def temp_tool() -> str:
return "Temporary tool"
# Mount the sub-app
main_app.mount("sub", sub_app)
# Initially, the tool should be accessible
tools = await main_app.get_tools()
assert "sub_temp_tool" in tools
# Remove the tool from sub_app
sub_app._tool_manager._tools.pop("temp_tool")
# The tool should no longer be accessible
# Refresh the cache by clearing it
main_app._cache.cache.clear()
tools = await main_app.get_tools()
assert "sub_temp_tool" not in tools
class TestResourcesAndTemplates:
"""Test mounting with resources and resource templates."""
async def test_mount_with_resources(self):
"""Test mounting a server with resources."""
main_app = FastMCP("MainApp")
data_app = FastMCP("DataApp")
@data_app.resource(uri="data://users")
async def get_users():
return ["user1", "user2"]
# Mount the data app
main_app.mount("data", data_app)
# Resource should be accessible through main app
resources = await main_app.get_resources()
assert "data://data/users" in resources
# Check that resource can be accessed
async with Client(main_app) as client:
result = await client.read_resource("data://data/users")
assert isinstance(result[0], TextResourceContents)
assert json.loads(result[0].text) == ["user1", "user2"]
async def test_mount_with_resource_templates(self):
"""Test mounting a server with resource templates."""
main_app = FastMCP("MainApp")
user_app = FastMCP("UserApp")
@user_app.resource(uri="users://{user_id}/profile")
def get_user_profile(user_id: str) -> dict:
return {"id": user_id, "name": f"User {user_id}"}
# Mount the user app
main_app.mount("api", user_app)
# Template should be accessible through main app
templates = await main_app.get_resource_templates()
assert "users://api/{user_id}/profile" in templates
# Check template instantiation
async with Client(main_app) as client:
result = await client.read_resource("users://api/123/profile")
assert isinstance(result[0], TextResourceContents)
profile = json.loads(result[0].text)
assert profile["id"] == "123"
assert profile["name"] == "User 123"
async def test_adding_resource_after_mounting(self):
"""Test adding a resource after mounting."""
main_app = FastMCP("MainApp")
data_app = FastMCP("DataApp")
# Mount the data app before adding resources
main_app.mount("data", data_app)
# Add a resource after mounting
@data_app.resource(uri="data://config")
def get_config():
return {"version": "1.0"}
# Resource should be accessible through main app
resources = await main_app.get_resources()
assert "data://data/config" in resources
# Check access to the resource
async with Client(main_app) as client:
result = await client.read_resource("data://data/config")
assert isinstance(result[0], TextResourceContents)
config = json.loads(result[0].text)
assert config["version"] == "1.0"
class TestPrompts:
"""Test mounting with prompts."""
async def test_mount_with_prompts(self):
"""Test mounting a server with prompts."""
main_app = FastMCP("MainApp")
assistant_app = FastMCP("AssistantApp")
@assistant_app.prompt()
def greeting(name: str) -> str:
return f"Hello, {name}!"
# Mount the assistant app
main_app.mount("assistant", assistant_app)
# Prompt should be accessible through main app
prompts = await main_app.get_prompts()
assert "assistant_greeting" in prompts
# Render the prompt
result = await main_app._mcp_get_prompt("assistant_greeting", {"name": "World"})
assert result.messages is not None
# The message should contain our greeting text
async def test_adding_prompt_after_mounting(self):
"""Test adding a prompt after mounting."""
main_app = FastMCP("MainApp")
assistant_app = FastMCP("AssistantApp")
# Mount the assistant app before adding prompts
main_app.mount("assistant", assistant_app)
# Add a prompt after mounting
@assistant_app.prompt()
def farewell(name: str) -> str:
return f"Goodbye, {name}!"
# Prompt should be accessible through main app
prompts = await main_app.get_prompts()
assert "assistant_farewell" in prompts
# Render the prompt
result = await main_app._mcp_get_prompt("assistant_farewell", {"name": "World"})
assert result.messages is not None
# The message should contain our farewell text
class TestProxyServer:
"""Test mounting a proxy server."""
async def test_mount_proxy_server(self):
"""Test mounting a proxy server."""
# Create original server
original_server = FastMCP("OriginalServer")
@original_server.tool()
def get_data(query: str) -> str:
return f"Data for {query}"
# Create proxy server
proxy_server = FastMCP.as_proxy(
Client(transport=FastMCPTransport(original_server))
)
# Mount proxy server
main_app = FastMCP("MainApp")
main_app.mount("proxy", proxy_server)
# Tool should be accessible through main app
tools = await main_app.get_tools()
assert "proxy_get_data" in tools
# Call the tool
result = await main_app._mcp_call_tool("proxy_get_data", {"query": "test"})
assert isinstance(result[0], TextContent)
assert result[0].text == "Data for test"
async def test_dynamically_adding_to_proxied_server(self):
"""Test that changes to the original server are reflected in the mounted proxy."""
# Create original server
original_server = FastMCP("OriginalServer")
# Create proxy server
proxy_server = FastMCP.as_proxy(
Client(transport=FastMCPTransport(original_server))
)
# Mount proxy server
main_app = FastMCP("MainApp")
main_app.mount("proxy", proxy_server)
# Add a tool to the original server
@original_server.tool()
def dynamic_data() -> str:
return "Dynamic data"
# Tool should be accessible through main app via proxy
tools = await main_app.get_tools()
assert "proxy_dynamic_data" in tools
# Call the tool
result = await main_app._mcp_call_tool("proxy_dynamic_data", {})
assert isinstance(result[0], TextContent)
assert result[0].text == "Dynamic data"
async def test_proxy_server_with_resources(self):
"""Test mounting a proxy server with resources."""
# Create original server
original_server = FastMCP("OriginalServer")
@original_server.resource(uri="config://settings")
def get_config():
return {"api_key": "12345"}
# Create proxy server
proxy_server = FastMCP.as_proxy(
Client(transport=FastMCPTransport(original_server))
)
# Mount proxy server
main_app = FastMCP("MainApp")
main_app.mount("proxy", proxy_server)
# Resource should be accessible through main app
result = await main_app._mcp_read_resource("config://proxy/settings")
assert isinstance(result[0], ReadResourceContents)
config = json.loads(result[0].content)
assert config["api_key"] == "12345"
async def test_proxy_server_with_prompts(self):
"""Test mounting a proxy server with prompts."""
# Create original server
original_server = FastMCP("OriginalServer")
@original_server.prompt()
def welcome(name: str) -> str:
return f"Welcome, {name}!"
# Create proxy server
proxy_server = FastMCP.as_proxy(
Client(transport=FastMCPTransport(original_server))
)
# Mount proxy server
main_app = FastMCP("MainApp")
main_app.mount("proxy", proxy_server)
# Prompt should be accessible through main app
result = await main_app._mcp_get_prompt("proxy_welcome", {"name": "World"})
assert result.messages is not None
# The message should contain our welcome text
class TestAsProxyKwarg:
"""Test the as_proxy kwarg."""
async def test_as_proxy_defaults_false(self):
mcp = FastMCP("Main")
sub = FastMCP("Sub")
mcp.mount("sub", sub)
assert mcp._mounted_servers["sub"].server is sub
async def test_as_proxy_false(self):
mcp = FastMCP("Main")
sub = FastMCP("Sub")
mcp.mount("sub", sub, as_proxy=False)
assert mcp._mounted_servers["sub"].server is sub
async def test_as_proxy_true(self):
mcp = FastMCP("Main")
sub = FastMCP("Sub")
mcp.mount("sub", sub, as_proxy=True)
assert mcp._mounted_servers["sub"].server is not sub
assert isinstance(mcp._mounted_servers["sub"].server, FastMCPProxy)
async def test_as_proxy_defaults_true_if_lifespan(self):
@asynccontextmanager
async def lifespan(mcp: FastMCP):
yield
mcp = FastMCP("Main")
sub = FastMCP("Sub", lifespan=lifespan)
mcp.mount("sub", sub)
assert mcp._mounted_servers["sub"].server is not sub
assert isinstance(mcp._mounted_servers["sub"].server, FastMCPProxy)
async def test_as_proxy_ignored_for_proxy_mounts_default(self):
mcp = FastMCP("Main")
sub = FastMCP("Sub")
sub_proxy = FastMCP.as_proxy(Client(transport=FastMCPTransport(sub)))
mcp.mount("sub", sub_proxy)
assert mcp._mounted_servers["sub"].server is sub_proxy
async def test_as_proxy_ignored_for_proxy_mounts_false(self):
mcp = FastMCP("Main")
sub = FastMCP("Sub")
sub_proxy = FastMCP.as_proxy(Client(transport=FastMCPTransport(sub)))
mcp.mount("sub", sub_proxy, as_proxy=False)
assert mcp._mounted_servers["sub"].server is sub_proxy
async def test_as_proxy_ignored_for_proxy_mounts_true(self):
mcp = FastMCP("Main")
sub = FastMCP("Sub")
sub_proxy = FastMCP.as_proxy(Client(transport=FastMCPTransport(sub)))
mcp.mount("sub", sub_proxy, as_proxy=True)
assert mcp._mounted_servers["sub"].server is sub_proxy
async def test_as_proxy_mounts_still_have_live_link(self):
mcp = FastMCP("Main")
sub = FastMCP("Sub")
mcp.mount("sub", sub, as_proxy=True)
assert len(await mcp.get_tools()) == 0
@sub.tool()
def hello():
return "hi"
assert len(await mcp.get_tools()) == 1
async def test_sub_lifespan_is_executed(self):
lifespan_check = []
@asynccontextmanager
async def lifespan(mcp: FastMCP):
lifespan_check.append("start")
yield
mcp = FastMCP("Main")
sub = FastMCP("Sub", lifespan=lifespan)
@sub.tool()
def hello():
return "hi"
mcp.mount("sub", sub, as_proxy=True)
assert lifespan_check == []
async with Client(mcp) as client:
await client.call_tool("sub_hello", {})
assert lifespan_check == ["start"]