def test_sortedReactorHelp(self):
        """
        Reactor names are listed alphabetically by I{--help-reactors}.
        """
        class FakeReactorInstaller(object):
            def __init__(self, name):
                self.shortName = 'name of ' + name
                self.description = 'description of ' + name
                self.moduleName = 'twisted.internet.default'

        apple = FakeReactorInstaller('apple')
        banana = FakeReactorInstaller('banana')
        coconut = FakeReactorInstaller('coconut')
        donut = FakeReactorInstaller('donut')

        def getReactorTypes():
            yield coconut
            yield banana
            yield donut
            yield apple

        config = twistd.ServerOptions()
        self.assertEqual(config._getReactorTypes, reactors.getReactorTypes)
        config._getReactorTypes = getReactorTypes
        config.messageOutput = NativeStringIO()

        self.assertRaises(SystemExit, config.parseOptions, ['--help-reactors'])
        helpOutput = config.messageOutput.getvalue()
        indexes = []
        for reactor in apple, banana, coconut, donut:
            def getIndex(s):
                self.assertIn(s, helpOutput)
                indexes.append(helpOutput.index(s))

            getIndex(reactor.shortName)
            getIndex(reactor.description)

        self.assertEqual(
            indexes, sorted(indexes),
            'reactor descriptions were not in alphabetical order: %r' % (
                helpOutput,))

        Reactor names are listed alphabetically by I{--help-reactors}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_twistd.py