'L{Team.grow} increases the number of available idle workers until the
C{createWorker} callable starts returning None.'

def test_growCreateLimit(self):

    self.noMoreWorkers = (lambda : (len(self.allWorkersEver) >= 3))
    self.team.grow(5)
    self.performAllOutstandingWork()
    self.assertEqual(len(self.allWorkersEver), 3)
    self.assertEqual(self.team.statistics().idleWorkerCount, 3)
