def test_osx(self):
        """
        L{_getInstallFunction} chooses the select reactor on macOS.
        """
        install = _getInstallFunction(osx)
        self.assertEqual(
            install.__module__, 'twisted.internet.selectreactor')

        L{_getInstallFunction} chooses the select reactor on macOS.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_default.py