def test_backwardsTLS(self):
        """
        Test startTLS first initiated by client.
        """
        def check(ignored):
            self.assertEqual(
                self.clientFactory.lines,
                UnintelligentProtocol.pretext + UnintelligentProtocol.posttext
            )
        d = self._runTest(LineCollector(True, self.fillBuffer),
                          UnintelligentProtocol(), True)
        return d.addCallback(check)

        Test startTLS first initiated by client.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ssl.py