Additional MCP and test clean-up

src/fastmcp/utilities/mcp_config.py

@@ -7,29 +7,6 @@ from fastmcp.mcp_config import (
 )
 from fastmcp.server.server import FastMCP
 
-# def composite_server_from_mcp_config(
-#     config: MCPConfig, name_as_prefix: bool = True
-# ) -> tuple[FastMCP[None], list[ClientTransport]]:
-#     """A utility function to create a composite server from an MCPConfig, returns the underlying
-#     transports for each server.
-#     """
-#     composite_server = FastMCP[None]()
-
-#     transports = mount_mcp_config_into_server(config, composite_server, name_as_prefix)
-
-#     return composite_server, transports
-
-
-# def mount_mcp_config_into_server(
-#     config: MCPConfig,
-#     server: FastMCP[Any],
-#     name_as_prefix: bool = True,
-# ) -> None:
-#     """A utility function to mount the servers from an MCPConfig into a FastMCP server, returns the underlying
-#     transports for each server.
-#     """
-#     for name, server_to_mount, transport in mcp_config_to_servers_and_transports(config):
-#         server.mount(server=server_to_mount, prefix=name if name_as_prefix else None)
 
 def mcp_config_to_servers_and_transports(
     config: MCPConfig,
@@ -40,6 +17,7 @@ def mcp_config_to_servers_and_transports(
         for name, mcp_server in config.mcpServers.items()
     ]
 
+
 def mcp_server_type_to_servers_and_transports(
     name: str,
     mcp_server: MCPServerTypes,
@@ -48,13 +26,12 @@ def mcp_server_type_to_servers_and_transports(
     from fastmcp.mcp_config import (
         TransformingRemoteMCPServer,
         TransformingStdioMCPServer,
-)
+    )
+
     server: FastMCP[Any]
     transport: ClientTransport
 
-    if isinstance(
-        mcp_server, TransformingRemoteMCPServer | TransformingStdioMCPServer
-    ):
+    if isinstance(mcp_server, TransformingRemoteMCPServer | TransformingStdioMCPServer):
         server, transport = mcp_server._to_server_and_transport()
     else:
         transport = mcp_server.to_transport()

tests/client/test_stdio.py

@@ -1,6 +1,7 @@
 import asyncio
 import gc
 import inspect
+import os
 import weakref
 
 import psutil
@@ -10,6 +11,10 @@ from fastmcp import Client
 from fastmcp.client.transports import PythonStdioTransport, StdioTransport
 
 
+def running_under_debugger():
+    return os.environ.get("DEBUGPY_RUNNING") == "true"
+
+
 def gc_collect_harder():
     gc.collect()
     gc.collect()
@@ -69,6 +74,9 @@ class TestKeepAlive:
 
         assert pid1 == pid2
 
+    @pytest.mark.skipif(
+        running_under_debugger(), reason="Debugger holds a reference to the transport"
+    )
     async def test_keep_alive_true_exit_scope_kills_transport(self, stdio_script):
         transport_weak_ref: weakref.ref[PythonStdioTransport] | None = None
 
@@ -83,12 +91,14 @@ class TestKeepAlive:
 
         gc_collect_harder()
 
-        # When debugging, the debugger holds extra references so this test
-        # will pass when running and fail under the debugger.
+        # This test will fail while debugging because the debugger holds a reference to the underlying transport
         assert transport_weak_ref
         transport = transport_weak_ref()
         assert transport is None
 
+    @pytest.mark.skipif(
+        running_under_debugger(), reason="Debugger holds a reference to the transport"
+    )
     async def test_keep_alive_true_exit_scope_kills_client(self, stdio_script):
         pid: int | None = None
 
@@ -107,6 +117,8 @@ class TestKeepAlive:
 
         gc_collect_harder()
 
+        # This test may fail/hang while debugging because the debugger holds a reference to the underlying transport
+
         with pytest.raises(psutil.NoSuchProcess):
             while True:
                 psutil.Process(pid)

tests/test_mcp_config.py

@@ -2,6 +2,7 @@ import asyncio
 import gc
 import inspect
 import logging
+import os
 import tempfile
 from collections.abc import AsyncGenerator
 from pathlib import Path
@@ -32,6 +33,10 @@ from fastmcp.mcp_config import (
 from fastmcp.tools.tool import Tool as FastMCPTool
 
 
+def running_under_debugger():
+    return os.environ.get("DEBUGPY_RUNNING") == "true"
+
+
 def gc_collect_harder():
     gc.collect()
     gc.collect()
@@ -237,6 +242,9 @@ async def test_multi_client(tmp_path: Path):
         assert result_2.data == 3
 
 
+@pytest.mark.skipif(
+    running_under_debugger(), reason="Debugger holds a reference to the transport"
+)
 async def test_multi_client_lifespan(tmp_path: Path):
     pid_1: int | None = None
     pid_2: int | None = None
@@ -285,6 +293,8 @@ async def test_multi_client_lifespan(tmp_path: Path):
 
     gc_collect_harder()
 
+    # This test will fail while debugging because the debugger holds a reference to the underlying transport
+
     with pytest.raises(psutil.NoSuchProcess):
         while True:
             psutil.Process(pid_1)
@@ -295,6 +305,7 @@ async def test_multi_client_lifespan(tmp_path: Path):
             psutil.Process(pid_2)
             await asyncio.sleep(0.1)
 
+
 async def test_multi_client_force_close(tmp_path: Path):
     server_script = inspect.cleandoc("""
         from fastmcp import FastMCP