def setUp(self):
        """
        Create class variables of client and server certificates.
        """
        self.sKey, self.sCert = makeCertificate(
            O=b"Server Test Certificate",
            CN=b"server")
        self.cKey, self.cCert = makeCertificate(
            O=b"Client Test Certificate",
            CN=b"client")
        self.caCert1 = makeCertificate(
            O=b"CA Test Certificate 1",
            CN=b"ca1")[1]
        self.caCert2 = makeCertificate(
            O=b"CA Test Certificate",
            CN=b"ca2")[1]
        self.caCerts = [self.caCert1, self.caCert2]
        self.extraCertChain = self.caCerts

        Create class variables of client and server certificates.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sslverify.py