def test_caCertsPlatformDefaults(self):
        """
        Specifying a C{trustRoot} of L{sslverify.OpenSSLDefaultPaths} when
        initializing L{sslverify.OpenSSLCertificateOptions} loads the
        platform-provided trusted certificates via C{set_default_verify_paths}.
        """
        opts = sslverify.OpenSSLCertificateOptions(
            trustRoot=sslverify.OpenSSLDefaultPaths(),
        )
        fc = FakeContext(SSL.TLSv1_METHOD)
        opts._contextFactory = lambda method: fc
        opts.getContext()
        self.assertTrue(fc._defaultVerifyPathsSet)

        Specifying a C{trustRoot} of L{sslverify.OpenSSLDefaultPaths} when
        initializing L{sslverify.OpenSSLCertificateOptions} loads the
        platform-provided trusted certificates via C{set_default_verify_paths}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sslverify.py