Seems WebOb 1.7 has some glitches with WebTest when a 204 is responded

[amol-]

The recent WebOb 1.7 changes to initialisation function seem to had introduced a side effect when WebTest is used, as webtest will recreate a new Response object from the application response.

A simple testcase can be created to showcase the issue:

from webob import Response

def wsgi_app(environ, start_response):
    resp = Response(status='204 No Content', body=b'')
    resp.content_type = None
    return resp(environ, start_response)

The snippet is meant to work on both 1.6 and 1.7, so it adds some unnecessary values like body and content_type which are already provided in 1.7 (those values are in fact a nop on 1.7) while they are required on 1.6 to generate a response without content.

The response is as expected both on 1.6 and 1.7

Response: 204 No Content

Creating a plain webtest TestApp from the previous example:

from webtest import TestApp

app = TestApp(wsgi_app)
app.get('/')

will issue a validation error on WebOb 1.7:

Iterator garbage collected without being closedException AssertionError: AssertionError('Iterator garbage collected without being closed',) in <bound method IteratorWrapper.__del__ of <webtest.lint.IteratorWrapper object at 0x100ed0850>> ignored

while it will work without the error with WebOb 1.6.

This seems to be related to 35fd585 as https://github.com/Pylons/webob/blob/master/webob/response.py#L323 throws away the webtest IteratorWrapper injected by WebTest replacing it with [b''] as code_has_body is False and thus breaking WebTest

I wouldn't take for granted that if there is an app_iter it will be wrong and needs to be discarded as response has no content. It's probably a right assumption in the case of body, but discarding app_iter might in fact break some application by discarding an iterator which returns an empty response too but has other side effects.

[digitalresistor]

Thanks for the report @amol-

It may be that if there is an app_iter provided that we set it explicitly, and let the user deal with the breakage if their app_iter contains data and it shouldn't.

[digitalresistor]

I have added a test and app_iter is now set on Response. New release is out: https://pypi.python.org/pypi/WebOb/1.7.1