fix: asgi lifespan msg after lifespan context exception (#3315)

An exception raised within an asgi lifespan context manager would result in a "lifespan.startup.failed" message being sent after we've already sent a "lifespan.startup.complete" message. This would cause uvicorn to raise a `STATE_TRANSITION_ERROR` assertion error due to their [check for that condition][1].

This PR modifies `ASGIRouter.lifespan()` so that it sends a shutdown failure message if we've already confirmed startup. This is consistent with [starlette's behavior][2] under the same conditions.

[1]: https://github.com/encode/uvicorn/blob/a2219eb2ed2bbda4143a0fb18c4b0578881b1ae8/uvicorn/lifespan/on.py#L115-L117
[2]: https://github.com/encode/starlette/blob/4e453ce91940cc7c995e6c728e3fdf341c039056/starlette/routing.py#L744-L745

litestar/_asgi/asgi_router.py

@@ -158,27 +158,28 @@ async def lifespan(self, receive: LifeSpanReceive, send: LifeSpanSend) -> None:
         Returns:
             None.
         """
-
-        message = await receive()
         shutdown_event: LifeSpanShutdownCompleteEvent = {"type": "lifespan.shutdown.complete"}
         startup_event: LifeSpanStartupCompleteEvent = {"type": "lifespan.startup.complete"}
 
+        await receive()
+
+        started = False
         try:
             async with self.app.lifespan():
                 await send(startup_event)
-                message = await receive()
+                started = True
+                await receive()
 
         except BaseException as e:
             formatted_exception = format_exc()
             failure_message: LifeSpanStartupFailedEvent | LifeSpanShutdownFailedEvent
 
-            if message["type"] == "lifespan.startup":
-                failure_message = {"type": "lifespan.startup.failed", "message": formatted_exception}
-            else:
+            if started:
                 failure_message = {"type": "lifespan.shutdown.failed", "message": formatted_exception}
+            else:
+                failure_message = {"type": "lifespan.startup.failed", "message": formatted_exception}
 
             await send(failure_message)
-
             raise e
 
         await send(shutdown_event)

tests/unit/test_asgi_router.py

@@ -2,8 +2,9 @@
 
 from contextlib import asynccontextmanager
 from typing import TYPE_CHECKING, AsyncGenerator, Callable
-from unittest.mock import AsyncMock, MagicMock
+from unittest.mock import AsyncMock, MagicMock, call
 
+import anyio
 import pytest
 from pytest_mock import MockerFixture
 
@@ -194,3 +195,33 @@ async def on_shutdown() -> None:
 
     assert send.call_count == 2
     assert send.call_args_list[1][0][0] == {"type": "lifespan.shutdown.failed", "message": mock_format_exc.return_value}
+
+
+async def test_lifespan_context_exception_after_startup(mock_format_exc: MagicMock) -> None:
+    receive = AsyncMock()
+    receive.return_value = {"type": "lifespan.startup"}
+    send = AsyncMock()
+    mock_format_exc.return_value = "foo"
+
+    async def sleep_and_raise() -> None:
+        await anyio.sleep(0)
+        raise RuntimeError("An error occurred")
+
+    @asynccontextmanager
+    async def lifespan(_: Litestar) -> AsyncGenerator[None, None]:
+        async with anyio.create_task_group() as tg:
+            tg.start_soon(sleep_and_raise)
+            yield
+
+    router = ASGIRouter(app=Litestar(lifespan=[lifespan]))
+
+    with pytest.raises(_ExceptionGroup):
+        await router.lifespan(receive, send)
+
+    assert receive.call_count == 2
+    send.assert_has_calls(
+        [
+            call({"type": "lifespan.startup.complete"}),
+            call({"type": "lifespan.shutdown.failed", "message": mock_format_exc.return_value}),
+        ]
+    )