test: use asynccontextmanager for FastAPI lifespan

tests/unit_tests/test_axon.py

@@ -1,18 +1,23 @@
+import asyncio
+import contextlib
 import re
+import threading
 import time
 from dataclasses import dataclass
 from typing import Any, Optional, Tuple
 from unittest import IsolatedAsyncioTestCase
 from unittest.mock import AsyncMock, MagicMock, patch
 
+import aiohttp
 import fastapi
 import netaddr
 import pydantic
 import pytest
+import uvicorn
 from fastapi.testclient import TestClient
 from starlette.requests import Request
 
-from bittensor.core.axon import AxonMiddleware, Axon
+from bittensor.core.axon import Axon, AxonMiddleware, FastAPIThreadedServer
 from bittensor.core.errors import RunException
 from bittensor.core.settings import version_as_int
 from bittensor.core.stream import StreamingSynapse
@@ -765,3 +770,50 @@ async def forward_fn(synapse: streaming_synapse_cls):
                 "computed_body_hash": "a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a",
             },
         )
+
+
+@pytest.mark.asyncio
+async def test_threaded_fastapi():
+    server_started = threading.Event()
+    server_stopped = threading.Event()
+
+    @contextlib.asynccontextmanager
+    async def lifespan(app):
+        server_started.set()
+        yield
+        server_stopped.set()
+
+    app = fastapi.FastAPI(
+        lifespan=lifespan,
+    )
+    app.get("/")(lambda: "Hello World")
+
+    server = FastAPIThreadedServer(
+        uvicorn.Config(app, loop="none"),
+    )
+    server.start()
+
+    server_started.wait(3.0)
+
+    async def wait_for_server():
+        while not (server.started or server_stopped.is_set()):
+            await asyncio.sleep(1.0)
+
+    await asyncio.wait_for(wait_for_server(), 7.0)
+
+    assert server.is_running is True
+
+    async with aiohttp.ClientSession(
+        base_url="http://127.0.0.1:8000",
+    ) as session:
+        async with session.get("/") as response:
+            assert await response.text() == '"Hello World"'
+
+        server.stop()
+
+        assert server.should_exit is True
+
+        server_stopped.wait()
+
+        with pytest.raises(aiohttp.ClientConnectorError):
+            await session.get("/")