test: add mcp e2e test

tests/mcp_tests/test_configs/test_config_mcp_e2e.yaml

@@ -0,0 +1,20 @@
+general_settings:
+  master_key: sk-1234
+
+litellm_settings:
+  drop_params: true
+
+model_list:
+  - model_name: openai-gpt-4o-mini
+    litellm_params:
+      model: gpt-4o-mini
+  - model_name: anthropic-claude-haiku-4-5
+    litellm_params:
+      model: anthropic/claude-haiku-4-5
+
+mcp_servers:
+  math_stdio:
+    transport: stdio
+    command: python3
+    args:
+      - tests/mcp_tests/mcp_server.py

tests/mcp_tests/test_proxy_mcp_e2e.py

@@ -0,0 +1,94 @@
+import asyncio
+import socket
+import threading
+import time
+from pathlib import Path
+
+import pytest
+import uvicorn
+from mcp import ClientSession
+from mcp.client.streamable_http import streamablehttp_client
+
+from litellm.proxy.proxy_server import (
+    app as proxy_app,
+    cleanup_router_config_variables,
+    initialize,
+)
+
+
+CONFIG_TEMPLATE_PATH = Path("tests/mcp_tests/test_configs/test_config_mcp_e2e.yaml")
+PROXY_START_TIMEOUT = 30
+MCP_HEADERS = {
+    "Authorization": "Bearer sk-1234",
+    "x-mcp-servers": "math_stdio",
+}
+
+
+def _initialize_proxy(config_path: str) -> None:
+    cleanup_router_config_variables()
+    asyncio.run(initialize(config=config_path, debug=True))
+
+
+def _start_proxy_server(config_path: str) -> tuple[str, uvicorn.Server, threading.Thread, socket.socket]:
+    _initialize_proxy(config_path)
+
+    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    sock.bind(("127.0.0.1", 0))
+    host, port = sock.getsockname()
+
+    config = uvicorn.Config(proxy_app, host=host, port=port, log_level="warning")
+    server = uvicorn.Server(config)
+
+    def _run() -> None:
+        loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(loop)
+        loop.run_until_complete(server.serve(sockets=[sock]))
+
+    thread = threading.Thread(target=_run, daemon=True)
+    thread.start()
+
+    start_time = time.time()
+    while not server.started:
+        if not thread.is_alive():
+            raise RuntimeError("Proxy server failed to start")
+        if time.time() - start_time > PROXY_START_TIMEOUT:
+            raise TimeoutError("Proxy server did not start in time")
+        time.sleep(0.05)
+
+    return f"http://{host}:{port}", server, thread, sock
+
+
+@pytest.fixture(scope="session")
+def proxy_server_url(tmp_path_factory: pytest.TempPathFactory):
+    config_dir = tmp_path_factory.mktemp("mcp_e2e")
+    config_path = config_dir / "config.yaml"
+    config_path.write_text(CONFIG_TEMPLATE_PATH.read_text())
+
+    server_url, server, thread, sock = _start_proxy_server(str(config_path))
+
+    yield server_url
+
+    server.should_exit = True
+    thread.join(timeout=10)
+    sock.close()
+
+
+@pytest.mark.asyncio
+async def test_proxy_mcp_stdio_roundtrip(proxy_server_url: str) -> None:
+    async with asyncio.timeout(20):
+        async with streamablehttp_client(
+            url=f"{proxy_server_url}/mcp", headers=MCP_HEADERS
+        ) as (read, write, _get_session_id):
+            async with ClientSession(read, write) as session:
+                await session.initialize()
+                tools_result = await session.list_tools()
+                assert any(tool.name.endswith("add") for tool in tools_result.tools)
+
+                result = await session.call_tool(
+                    "add", arguments={"a": 3, "b": 4}
+                )
+                assert result.content
+                first_content = result.content[0]
+                text = getattr(first_content, "text", None)
+                assert text == "7"