'If a signal handler is already installed,
L{UnixAppLogger._getLogObserver} doesn\'t override it.'

def test_getLogObserverDontOverrideSignalHandler(self):

    def fakeGetSignal(sig):
        self.assertEqual(sig, signal.SIGUSR1)
        return object()
    self.patch(signal, 'getsignal', fakeGetSignal)
    filename = self.mktemp()
    logger = UnixAppLogger({'logfile': filename})
    logger._getLogObserver()
    self.assertEqual(self.signals, [])
