def test_fromFile(self):
        """
        Calling C{fromFile} with a filename returns an instance with that file
        name saved.
        """
        params = sslverify.OpenSSLDiffieHellmanParameters.fromFile(
            self.filePath
        )
        self.assertEqual(self.filePath, params._dhFile)

        Calling C{fromFile} with a filename returns an instance with that file
        name saved.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sslverify.py