Ensure error is raised when reading from closed client response.

CHANGES/8878.bugfix.rst

@@ -0,0 +1 @@
+Fixed response reading from closed session to throw an error immediately instead of timing out -- by :user:`Dreamsorcerer`.

aiohttp/streams.py

@@ -298,6 +298,9 @@ def end_http_chunk_receiving(self) -> None:
             set_result(waiter, None)
 
     async def _wait(self, func_name: str) -> None:
+        if not self._protocol.connected:
+            raise RuntimeError("Connection closed.")
+
         # StreamReader uses a future to link the protocol feed_data() method
         # to a read coroutine. Running two read coroutines at the same time
         # would have an unexpected behaviour. It would not possible to know

tests/test_client_functional.py

@@ -3777,3 +3777,20 @@ async def handler(_: web.Request) -> web.Response:
     ) as exc_info:
         await client.get("/")
     assert exc_info.value.status == 400
+
+
+async def test_exception_when_read_outside_of_session(
+    aiohttp_server: AiohttpServer,
+) -> None:
+    async def handler(request: web.Request) -> web.Response:
+        return web.Response(body=b"1" * 1000000)
+
+    app = web.Application()
+    app.router.add_get("/", handler)
+
+    server = await aiohttp_server(app)
+    async with aiohttp.ClientSession() as sess:
+        resp = await sess.get(server.make_url("/"))
+
+    with pytest.raises(RuntimeError, match="Connection closed"):
+        await resp.read()