streaming not working with newer versions of starlette about async-asgi-testclient

[masipcat]

Hi @falkben

Thank you for your detailed report.

It seems that starlette doesn't like reading the request body after starting the response. I changed the test to consume the request body and then start the response and this seems to work fine (#57).

I also created this example app without asgi-testclient to be sure it's not a bug in the test client, and it seems that the problem is in starlette:

# example.py
from starlette.applications import Starlette
from starlette.responses import StreamingResponse

app = Starlette()


async def buffered(request):
    chunks = [chunk async for chunk in request.stream()]

    async def gen(chunks):
        for chunk in chunks:
            yield chunk

    return StreamingResponse(gen(chunks))


async def unbuffered(request):
    return StreamingResponse(request.stream())

app.add_route("/buffered", buffered, methods=["POST"])
app.add_route("/unbuffered", unbuffered, methods=["POST"])

"""
1. Create a test file
dd if=/dev/urandom of=./file count=1024 bs=1024

2. Run server
uvicorn example:app

3. Check buffered stream works
curl -v -X POST localhost:8000/buffered --data-binary @file --output -

4. Test unbuffered stream doesn't work (empty response)
curl -v -X POST localhost:8000/unbuffered --data-binary @file --output -
"""

I was going to open a discussion in Starlette but I found this one reporting a similar problem