aconnect_ws does not work with AsyncClient bound to an app

[pavelschon]

Describe the bug

aconnect_ws does not work with an app which is bound to an existing FastAPI app.

To Reproduce

@pytest.fixture(name="client")
async def fixture_client(api: FastAPI) -> AsyncIterator[AsyncClient]:
    async with AsyncClient(app=api, base_url="http://test") as client:
        yield client

async def test_websocket(client: AsyncClient) -> None:
    async with aconnect_ws("/ws/", client) as ws:
        data = await ws.receive_json()

I get:

    @contextlib.asynccontextmanager
    async def _aconnect_ws(
        url: str,
        client: httpx.AsyncClient,
        *,
        max_message_size_bytes: int = DEFAULT_MAX_MESSAGE_SIZE_BYTES,
        queue_size: int = DEFAULT_QUEUE_SIZE,
        keepalive_ping_interval_seconds: typing.Optional[
            float
        ] = DEFAULT_KEEPALIVE_PING_INTERVAL_SECONDS,
        keepalive_ping_timeout_seconds: typing.Optional[
            float
        ] = DEFAULT_KEEPALIVE_PING_TIMEOUT_SECONDS,
        subprotocols: typing.Optional[typing.List[str]] = None,
        **kwargs: typing.Any,
    ) -> typing.AsyncGenerator[AsyncWebSocketSession, None]:
        headers = kwargs.pop("headers", {})
        headers.update(_get_headers(subprotocols))
    
        async with client.stream("GET", url, headers=headers, **kwargs) as response:
            if response.status_code != 101:
>               raise WebSocketUpgradeError(response)
E               httpx_ws._exceptions.WebSocketUpgradeError: <Response [404 Not Found]>

Obviously, the endpoint /ws/ exists within the app.

Expected behavior

It should call directly the FastAPI app, no TCP/HTTP connection should be made.

Configuration

• Python version: 3.12
• httpx-ws version: 0.5.1

[frankie567]

That's explained in the docs. You can't use the app= parameter (side note: it'll also be deprecated in HTTPX); you need to pass a specific transport: https://frankie567.github.io/httpx-ws/usage/asgi/

[pavelschon]

Well, there's another error:

    def __init__(
        self,
        stream: AsyncNetworkStream,
        *,
        max_message_size_bytes: int = DEFAULT_MAX_MESSAGE_SIZE_BYTES,
        queue_size: int = DEFAULT_QUEUE_SIZE,
        keepalive_ping_interval_seconds: typing.Optional[
            float
        ] = DEFAULT_KEEPALIVE_PING_INTERVAL_SECONDS,
        keepalive_ping_timeout_seconds: typing.Optional[
            float
        ] = DEFAULT_KEEPALIVE_PING_TIMEOUT_SECONDS,
        subprotocol: typing.Optional[str] = None,
    ) -> None:
        self.stream = stream
        self.connection = wsproto.connection.Connection(wsproto.ConnectionType.CLIENT)
        self.subprotocol = subprotocol
    
>       self._send_event, self._receive_event = anyio.create_memory_object_stream[
            typing.Union[wsproto.events.Event, HTTPXWSException]
        ]()
E       TypeError: 'function' object is not subscriptable

It seems I have obsolete anyio (3.7.1), where the method create_memory_object_stream was not yet generic.
But since httpx_ws does not depend on any specific version of anyio, then the dependency was satisfied.

After tweaking into

self._send_event, self._receive_event = anyio.create_memory_object_stream()

it works.

To me it looks like a small bug at this line: https://github.com/frankie567/httpx-ws/blob/main/pyproject.toml#L80

[frankie567]

Hey! Sorry, I missed your answer 🙂

You're right, we should have a lower bound version for anyio. I'll fix it.