[Twisted-Python] Using a custom reactor in twisted trial for test cases?

[Crispin Wellington]

On Mon, 2009-11-02 at 01:12 -0500, Glyph Lefkowitz wrote:
> On Nov 1, 2009, at 11:17 PM, Crispin Wellington wrote:

> > I tried using LoopingCall, but it does not work. It only calls the
> > scheduler once. I think this has to do with the fact that the  
> > stackless
> > scheduler needs to be interwoven with the twisted reactor pump.

> What do you mean "does not work"?

OK. Having a closer look, its not that looping call doesn't work, its
that there is some unknown number of "reactor pumps" between starting
the test, and finishing it. What I need is a way for the reactor to be
pumping away while a particular test function of a testcase continues
working. As an example, here is a non-working test case. Notice the
comment "#what to do here to pump the reactor?".

------------------
from twisted.trial import unittest, reporter, runner
import os, time
import stackless

from twisted.internet import reactor, task

def example_func(t=10.0):
    """wait for t seconds then return"""
    exit_time = time.time()+t
    while time.time()<exit_time:
        stackless.schedule()

t = task.LoopingCall(stackless.schedule)
t.start(0.1)

class StacklessTest(unittest.TestCase):
    def setUpClass(self):
        pass
        
    def test_stackless(self):
        """Test that we can successfuly create a user proxy cert"""
        # get the time now...
        start = time.time()
        
        task = stackless.tasklet(example_func)
        task.setup(10.0)
        task.run()
            
        while task.alive:
            pass            #what to do here to pump the reactor?
            
        # end time
        end = time.time()
            
        self.assert_( endtime - starttime >= 10.0 )
        
---------------------

Running this under trial, it just hangs, inside the while task.alive:
loop.

So I guess my problem is my approach. How do I test long running
"tasklets" that use twisted calls (unlike this contrived example that
only sleeps) within the twisted trial framework?

How would the Twisted experts write test code for a case like this? Any
help is much appreciated!

Kind Regards

Crispin Wellington