Testclient does not treat readable data correctly

[plankthom]

I think this is a potential issue with the TestClient

When posting streaming data, a client call like

with open(archive_path, 'rb') as archive_file:
    requests.put(url, headers={'Content-Type': 'application/gzip'}, data=archive_file) 

can be processed by a server route with a helper method

async def _write_request_stream(request: Request, target: BufferedWriter):
     async for data in request.stream():
         target.write(data)

However this doesn't work with the TestClient, i needed the following workaround on the server

from shutil import copyfileobj as copybuffers

async def _write_request_stream(request: Request, target: BufferedWriter):
     async for data in request.stream():
        if isinstance(data, BufferedReader):
            copybuffers(data, target)
        else:
            target.write(data)

IMO the test client should treat body arguments with a read method as the requests library does, converting it to chunks:
https://github.com/python/cpython/blob/c26af2bc531eb114c378cdad81935f6e838a7ee0/Lib/http/client.py#L1045

There seems to be some handling for a request body that is a generator, See https://github.com/encode/starlette/blob/87641dc8e7e72755f1b8f39dfc9b3bfbdf41c923/starlette/testclient.py#L212 ,
but IMO this should be extended to all body arguments that have a read method (for compatibility with the requests library)

Shall I create an issue , and maybe contribute a PR?

[Kludex]

We changed the HTTP client from requests to httpx, is this still an issue?

[Kludex]

I'll preemptively close this as outdated, but please let me know.