def _check(self):
        c2 = self._loggedErrors()
        self.assertEquals(len(c2), 2)
        c2[1]["failure"].trap(ZeroDivisionError)
        self.flushLoggedErrors(ZeroDivisionError)
Check the output of the log observer to see if the error is present.
dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/test/test_defer.py/LogTestCase._check