[Twisted-Python] Testing with trial, adbapi questions

[Christian Simms]

On 7/20/07, Brendon Colby <brendoncolby at gmail.com> wrote:
>
> On 6/26/07, Christian Simms <christian.simms at gmail.com> wrote:
> >
> > Looks like I mis-assumed your problem, sorry.  In the setUp method in
> > your tests, you should return a Deferred which fires when all your data is
> > loaded.  This can be a pain if you already organized your code into classes
> > inheriting from twisted.application.service.Service which have
> > startService/stopService calls. It's a pain because trial doesn't create an
> > application object like running inside twistd does.  So, in the case of
> > writing unit tests for applications, you can abstract out your
> > initialization code into a method, and then call that method directly in
> > your setUp method.
>
>
> I've spent some time working on this, and I see the logic in doing so
> (firing a deferred when my data is loaded) but I'm stuck at the point of how
> to do this. In my factory, I call this method in __init__ to load data:
>
>   def loadDevelopers(self):
>     def cb(results):
>       for result in results:
>         self.addDeveloper
> (Developer(result['auth_host'],result['auth_url'],
>           result['devid'],self,result['key'],result['post_host'],
>           result['post_url']))
>     return self.dbPool.runQuery("select * from developers where
> active=1").\
>       addCallback(cb).addErrback(printError)
>
> I created a tac file and am using twistd to run this and it works great.
> But in my unit tests, what happens is my tests run before my data is loaded
> (and fail). I haven't been able to figure out how to tell my tests to run
> after this data is loaded. Here's my setUp method:
>
>     def setUp(self):
>         self.file = StringIOWithoutClosing()
>         self.transport = FileWrapperThatWorks(self.file)
>         self.protocol = sserver.SServerProtocol()
>         self.protocol.factory = sserver.SServerFactory(self.protocol)
>         self.protocol.factory.dbPool.start()
>         self.protocol.makeConnection(self.transport)
>
>     def testSendDeveloperID(self):
>         print self.protocol.factory.developers # This dictionary prints as
> empty - it shouldn't!
>
> I guess I'm not making the connection here. How do I code the deferred in
> setUp to fire when my data is loaded? Also, if I abstract out this logic to
> an initialization method, how would I have it fire properly when I run under
> twistd? Here's my tac file:
>
> factory = SServerFactory(protocol=SServerProtocol)
> application = service.Application("SServer")
> sserverService = internet.TCPServer(4000,factory)
> sserverService.setServiceParent(application)
>
> I appreciate the help!
>
> Brendon
>
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>
>
To fix your unit tests to "wait" until your data is loaded by your
loadDevelopers method, you need to have your setUp method return the
Deferred created by loadDevelopers's. There are a bunch of ways to do this,
the simplest is probably to have your factory's __init__ method store the
Deferred created by loadDevelopers into a member variable (say self.deferred),
and then add a new line to the end of your setUp method above:

           return self.deferred

This way, each unit test will not start until the Deferred from
loadDevelopers fires.

Cheers,
Christian
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