def test_deprecated(self):
        """
        L{SSHPublicKeyDatabase} is deprecated as of version 15.0
        """
        warningsShown = self.flushWarnings(
            offendingFunctions=[self.setUp])
        self.assertEqual(warningsShown[0]['category'], DeprecationWarning)
        self.assertEqual(
            warningsShown[0]['message'],
            "twisted.conch.checkers.SSHPublicKeyDatabase "
            "was deprecated in Twisted 15.0.0: Please use "
            "twisted.conch.checkers.SSHPublicKeyChecker, "
            "initialized with an instance of "
            "twisted.conch.checkers.UNIXAuthorizedKeysFiles instead.")
        self.assertEqual(len(warningsShown), 1)

        L{SSHPublicKeyDatabase} is deprecated as of version 15.0
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_checkers.py