process_request Middlewhere failing during falcon simulated tests

[jamesjarvis]

When attempting to use falcons inbuilt request simulation, Falcon throws an assertion error due to the middleware not passing the required parameters to req.stream.read(): pytest output:

    def test_post(client, mock_mongo):
        test_obj = {}
    
>       resp = client.simulate_post(URL, body=json.dumps(test_obj))

tests/acceptance/test_stuff:107: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
venv/lib/python3.7/site-packages/falcon/testing/client.py:711: in simulate_post
    return self.simulate_request('POST', path, **kwargs)
venv/lib/python3.7/site-packages/falcon/testing/client.py:764: in simulate_request
    return simulate_request(self.app, *args, **kwargs)
venv/lib/python3.7/site-packages/falcon/testing/client.py:348: in simulate_request
    iterable = validator(env, srmock)
/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/wsgiref/validate.py:181: in lint_app
    iterator = application(environ, start_response_wrapper)
venv/lib/python3.7/site-packages/falcon/api.py:231: in __call__
    process_request(req, resp)
venv/lib/python3.7/site-packages/falcon_jsonify/__init__.py:97: in process_request
    body = req.stream.read()
/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/wsgiref/validate.py:197: in read
    assert_(len(args) == 1)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

cond = False, args = ()

    def assert_(cond, *args):
        if not cond:
>           raise AssertionError(*args)
E           AssertionError

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/wsgiref/validate.py:128: AssertionError

This can be fixed by using the workaround suggested here: https://falcon.readthedocs.io/en/stable/api/request_and_response.html#falcon.Request.stream

# If Content-Length happens to be 0, or the header is
# missing altogether, this will not block.
data = req.stream.read(req.content_length or 0)

Without this, any simulated post calls or calls with an expected body seem to fail.

[VDuda]

@AndreiRegiani Can you take a look at this? I also just ran into this issue. Sending a post with a data body fails without this fix.

i.e the following post would fail - since the middleware will fail to read the body

echo '{"number": "5"}' | http -v POST localhost:8001/create