def test_twisted(self):
        """Invoking python -m twisted should execute twist."""
        cmd = sys.executable
        p = Accumulator()
        d = p.endedDeferred = defer.Deferred()
        reactor.spawnProcess(p, cmd, [cmd, '-m', 'twisted', '--help'], env=None)
        p.transport.closeStdin()

        # Fix up our sys args to match the command we issued
        from twisted import __main__
        self.patch(sys, 'argv', [__main__.__file__, '--help'])

        def processEnded(ign):
            f = p.outF
            output = f.getvalue().replace(b'\r\n', b'\n')

            options = TwistOptions()
            message = '{}\n'.format(options).encode('utf-8')
            self.assertEqual(output, message)
        return d.addCallback(processEnded)
Invoking python -m twisted should execute twist.
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_main.py