httpx.RequestNotRead: Attempted to access request content, without having called `read()`

I would like to test if a client uses the REST interface in a proper way. I wanted to use respx to mock the HTTP requests. I found no easy way to test the content of the HTTP request sent to the service.

What I would expect:

• I can use the content attribute on the Request object returned by the calls to verify correctness of the request.

What happens:

• Accessing the content attribute throws an httpx.RequestNotRead exception
• The workaround I have found is to access the stream._body attribute which is kind of a hack. Or maybe I don not use the library in a proper way and the documentation should show this kind of example.

Used Environment:

• Python 3.8.5
• pytest 6.0.2
• httpx 0.15.5
• respx 0.13.0

Here the minimal example code:

import json
import respx
import httpx


def my_client():
    httpx.post("http://www.example.com/entries", content=json.dumps({"id": "1234567"}))
    return True


@respx.mock
def test_rest_call():
    """If the client sends the correct HTTP request - url and content."""
    respx.post(
        "http://www.example.com/entries",
        alias="example",
    )
    my_client()
    assert respx.aliases["example"].called
    assert respx.aliases["example"].call_count == 1
    request,_ = respx.aliases["example"].calls[0]
    
    # This works but is kinda ugly
    assert request.stream._body == '{"id": "1234567"}'.encode()
    # Would expect to work, but throws exception 'httpx.RequestNotRead'
    assert request.content == '{"id": "1234567"}'.encode()

Calling this with pytest:

$ pytest tests/test_request.py 
============================================================ test session starts =============================================================
platform linux -- Python 3.8.5, pytest-6.0.2, py-1.9.0, pluggy-0.13.1
rootdir: /home/max/work/iov42/python/core-sdk-python
plugins: xdoctest-0.15.0, typeguard-2.9.1
collected 1 item                                                                                                                             

tests/test_request.py F                                                                                                                [100%]

================================================================== FAILURES ==================================================================
_______________________________________________________________ test_rest_call _______________________________________________________________

    @respx.mock
    def test_rest_call():
        respx.post(
            "http://www.example.com/entries",
            alias="example",
        )
        my_client()
        assert respx.aliases["example"].called
        assert respx.aliases["example"].call_count == 1
        request,_ = respx.aliases["example"].calls[0]
    
        # This works but is kinda ugly
        assert request.stream._body == '{"id": "1234567"}'.encode()
        # Would expect to work, but does not work
>       assert request.content == '{"id": "1234567"}'.encode()

tests/test_request.py:26: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <Request('POST', 'http://www.example.com/entries')>

    @property
    def content(self) -> bytes:
        if not hasattr(self, "_content"):
>           raise RequestNotRead()
E           httpx.RequestNotRead: Attempted to access request content, without having called `read()`.

/home/max/.cache/pypoetry/virtualenvs/iov42-core-python-4oIM64sE-py3.8/lib/python3.8/site-packages/httpx/_models.py:823: RequestNotRead
========================================================== short test summary info ===========================================================
FAILED tests/test_request.py::test_rest_call - httpx.RequestNotRead: Attempted to access request content, without having called `read()`.
============================================================= 1 failed in 0.17s ==============================================================