I observed a bug when using StubTreq for testing a twisted.web.Resource using request.getSession() to store data between requests. Below is a rather dry report and my proposal for fixing this bug.
Expected behavior
When using treq.testing.StubTreq(some_resource) to make requests to the wrapped resource, the wrapped resource should be able to obtain the same twisted.web.server.Session instance every time request.getSession() is called in one of its render*(request) methods (provided that the same cookies parameter is supplied for every request).
Observed behavior
Even with proper cookies being set, calling request.getSession() in the wrapped resource returns a twisted.web.server.Session instance with a different uid. I confirmed that the TWISTED_SESSION cookie was used for both requests.
Debugging result
Each twisted.web.server.Session instance is stored in the twisted.web.server.Site instance. treq.testing.StubTreq, or more precisely treq.testing.RequestTraversalAgent creates a new twisted.web.server.Site instance for each request. Thus, the sessions aren't stored between requests.
Fix
Changing treq.testing.RequestTraversalAgent so that the serverFactory variable is moved from .request() to .__init__() and made an attribute of the treq.testing.RequestTraversalAgent shared between requests seems to fix this. Of course, the subsequent references to serverFactory must also be changed to the new attribute instead.
However, this introduces a new semi-problem: When using StubTreq for testing (which it likely will be used for) in combination with sessions makes it easy to leave a dirty reactor behind. This is caused by the DelayedCalls to Session.expire(), thus manual cleanup is needed. Changing StubTreq to make the _agent also a permanent attribute allows manual cleanup by directly expiring the sessions on tearDown() . This, however, is a rather 'ugly' affair. Thus, I want to propose to also add a cleanSessions() (or a more generic clean()) method to treq.testing.StubTreq to offer the user a simple way of cleaning the reactor when sessions were used.
twm
commented
3 years ago
Hi,
I observed a bug when using
StubTreqfor testing atwisted.web.Resourceusingrequest.getSession()to store data between requests. Below is a rather dry report and my proposal for fixing this bug.Expected behavior
When using
treq.testing.StubTreq(some_resource)to make requests to the wrapped resource, the wrapped resource should be able to obtain the sametwisted.web.server.Sessioninstance every timerequest.getSession()is called in one of itsrender*(request)methods (provided that the samecookiesparameter is supplied for every request).Observed behavior
Even with proper cookies being set, calling
request.getSession()in the wrapped resource returns atwisted.web.server.Sessioninstance with a differentuid. I confirmed that theTWISTED_SESSIONcookie was used for both requests.Debugging result
Each
twisted.web.server.Sessioninstance is stored in thetwisted.web.server.Siteinstance.treq.testing.StubTreq, or more preciselytreq.testing.RequestTraversalAgentcreates a newtwisted.web.server.Siteinstance for each request. Thus, the sessions aren't stored between requests.Fix
Changing
treq.testing.RequestTraversalAgentso that theserverFactoryvariable is moved from.request()to.__init__()and made an attribute of thetreq.testing.RequestTraversalAgentshared between requests seems to fix this. Of course, the subsequent references toserverFactorymust also be changed to the new attribute instead.However, this introduces a new semi-problem: When using
StubTreqfor testing (which it likely will be used for) in combination with sessions makes it easy to leave a dirty reactor behind. This is caused by theDelayedCalls toSession.expire(), thus manual cleanup is needed. ChangingStubTreqto make the_agentalso a permanent attribute allows manual cleanup by directly expiring the sessions ontearDown(). This, however, is a rather 'ugly' affair. Thus, I want to propose to also add acleanSessions()(or a more genericclean()) method totreq.testing.StubTreqto offer the user a simple way of cleaning the reactor when sessions were used.