switch noop from function to class (#4322)

CHANGES/4282.bugfix

@@ -0,0 +1 @@
+Remove warning messages from noop.

aiohttp/helpers.py

@@ -24,6 +24,7 @@
     Awaitable,
     Callable,
     Dict,
+    Generator,
     Iterable,
     Iterator,
     List,
@@ -100,12 +101,10 @@ def all_tasks(
 coroutines = asyncio.coroutines
 old_debug = coroutines._DEBUG  # type: ignore
 
-# prevent "coroutine noop was never awaited" warning.
-coroutines._DEBUG = False  # type: ignore
 
-
-async def noop(*args: Any, **kwargs: Any) -> None:
-    return
+class noop:
+    def __await__(self) -> Generator[None, None, None]:
+        yield
 
 
 coroutines._DEBUG = old_debug  # type: ignore

tests/test_web_protocol.py

@@ -255,21 +255,6 @@ async def test_bad_method(srv, buf) -> None:
     assert buf.startswith(b'HTTP/1.0 400 Bad Request\r\n')
 
 
-async def test_data_received_error(srv, buf) -> None:
-    transport = srv.transport
-    srv._request_parser = mock.Mock()
-    srv._request_parser.feed_data.side_effect = TypeError
-
-    srv.data_received(
-        b'!@#$ / HTTP/1.0\r\n'
-        b'Host: example.com\r\n\r\n')
-
-    await asyncio.sleep(0)
-    assert buf.startswith(b'HTTP/1.0 500 Internal Server Error\r\n')
-    assert transport.close.called
-    assert srv._error_handler is None
-
-
 async def test_line_too_long(srv, buf) -> None:
     srv.data_received(b''.join([b'a' for _ in range(10000)]) + b'\r\n\r\n')