unittest for threading function always failed...

[i3dmaster]

I am having a little difficulty to figure out why this unittest for a
Thread subclass always fails...


# unittest code:

class SPThreadUnitTest(unittest.TestCase):

  def testgetresult(self):
    from random import randint
    self.i = randint(1,10)
    def p(n): return n
    self.t = spthread.SPThread(target=p, args=(self.i))
    self.t.start()
    #self.t._res = self.t._target(self.t._args)
    self.assertEquals(self.i,self.t.getresult())


#spthread.SPThread code:

import threading
class SPThread(threading.Thread):

  def __init__(self,target=None,args=None):
    threading.Thread.__init__(self)
    self._target = target
    self._args = args
    self._res = None

  def getresult(self):
    return self._res

  def run(self):
    self._res = self._target(self._args)


A simple little test. But no matter what, the self._res didn't get any
value but None, so the assertion of self.i and self.t.getresult()
always fails. If I use the commented out code, it works. So the
start() function has some tricky stuff? Can someone point me out where
the problem is?

Thanks,
Jim