`ASGIWebSocketTransport` does not respect the response headers of the ASGI app during WebSocket handshake.

[WSH032]

Describe the bug

When testing with ASGIWebSocketTransport, it does not respect the response headers returned by the ASGI app, which includes the subprotocol header accepted by the app.

To Reproduce

import asyncio

import httpx
from fastapi import FastAPI
from httpx_ws import WebSocketDisconnect, aconnect_ws
from httpx_ws.transport import ASGIWebSocketTransport
from starlette.websockets import WebSocket

app = FastAPI()

@app.websocket("/")
async def _(ws: WebSocket):
    await ws.accept(subprotocol="foo")  # accept `foo` subprotocol
    await asyncio.sleep(0.1)
    await ws.close(1000, "bar")

httpx_client = httpx.AsyncClient(transport=ASGIWebSocketTransport(app=app))

async with aconnect_ws(
    "ws://www.example.com/", subprotocols=["foo", "bar"], client=httpx_client
) as ws:
    print(ws.subprotocol)  # expect `foo` but get `None`
    await asyncio.sleep(0.2)
    await ws.close(1000, "baz")

assert ws.subprotocol == "foo"  # AssertionError

Expected behavior

https://github.com/frankie567/httpx-ws/blob/1e1c252c2b678f8cc475e1c1546980a784f19702/httpx_ws/transport.py#L185

This code should not be hard-coded to generate a fixed response; rather, it should return the response generated by the app.

Configuration

• Python version: py3.10
• httpx-ws version: 0.4.2

Additional context

None.

[frankie567]

Thank you for the detailed report @WSH032! That was indeed a miss in the implementation. FIxed in a43a1e256d8f07ad2b986210af21e18818cc2a4f