Ensure socket aclose checkpoints after closing

docs/versionhistory.rst

@@ -68,6 +68,9 @@ This library adheres to `Semantic Versioning 2.0 <http://semver.org/>`_.
 - Fixed ``UNIXSocketStream.aclose()`` raising ``asyncio.InvalidStateError`` when a
   concurrent receive or send operation had just been cancelled on the asyncio backend
   (`#1267 <https://github.com/agronholm/anyio/issues/1267>`_; PR by @alloutflo)
+- Fixed socket ``aclose()`` implementations not checkpointing after closing on the
+  asyncio and Trio backends
+  (`#1288 <https://github.com/agronholm/anyio/issues/1288>`_; PR by @hansu650)
 - Fixed the pytest plugin importing the deprecated ``_pytest.python.CallSpec2`` alias,
   which triggers ``PytestRemovedIn10Warning`` on ``pytest>=9.2`` and crashes pytest at
   startup when ``filterwarnings = error`` is configured

src/anyio/_backends/_asyncio.py

@@ -1453,6 +1453,8 @@ async def aclose(self) -> None:
             if self._send_future and not self._send_future.done():
                 self._send_future.set_result(None)
 
+        await AsyncIOBackend.checkpoint()
+
 
 class UNIXSocketStream(_RawSocketMixin, abc.UNIXSocketStream):
     async def send_eof(self) -> None:

src/anyio/_backends/_trio.py

@@ -467,6 +467,8 @@ async def aclose(self) -> None:
             self._closed = True
             self._trio_socket.close()
 
+        await trio.lowlevel.checkpoint()
+
     def _convert_socket_error(self, exc: BaseException) -> NoReturn:
         if isinstance(exc, trio.ClosedResourceError):
             raise ClosedResourceError from exc

tests/test_sockets.py

@@ -37,6 +37,7 @@
 from anyio import (
     BrokenResourceError,
     BusyResourceError,
+    CancelScope,
     ClosedResourceError,
     EndOfStream,
     Event,
@@ -54,6 +55,7 @@
     create_unix_datagram_socket,
     create_unix_listener,
     fail_after,
+    get_cancelled_exc_class,
     getaddrinfo,
     getnameinfo,
     move_on_after,
@@ -1499,6 +1501,19 @@ async def operate() -> None:
             if client is not None:
                 await client.aclose()
 
+    async def test_aclose_checkpoints_when_cancelled(
+        self, server_sock: socket.socket, socket_path: Path
+    ) -> None:
+        stream = await connect_unix(socket_path)
+        raw_socket = stream.extra(SocketAttribute.raw_socket)
+
+        with CancelScope() as scope:
+            scope.cancel()
+            with pytest.raises(get_cancelled_exc_class()):
+                await stream.aclose()
+
+        assert raw_socket.fileno() == -1
+
     async def test_receive_after_close(
         self, server_sock: socket.socket, socket_path: Path
     ) -> None: