def test_noOpenSSL(self):
        """
        If SSL is not supported, L{TLSMemoryBIOFactory} will be L{None}, which
        causes C{_wrapper} to also be L{None}.  If C{_wrapper} is L{None}, then
        an exception is raised.
        """
        replaced = replacingGlobals(endpoints.wrapClientTLS,
                                    TLSMemoryBIOFactory=None)
        notImplemented = self.assertRaises(NotImplementedError, replaced,
                                           None, None)
        self.assertIn("OpenSSL not available", str(notImplemented))

        If SSL is not supported, L{TLSMemoryBIOFactory} will be L{None}, which
        causes C{_wrapper} to also be L{None}.  If C{_wrapper} is L{None}, then
        an exception is raised.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py