'If an extension requires a subject, the :py:data:`subject` parameter to
:py:class:`X509Extension` provides its value.'

def test_subject(self):

    ext3 = X509Extension(b('subjectKeyIdentifier'), False, b('hash'), subject=self.x509)
    self.x509.add_extensions([ext3])
    self.x509.sign(self.pkey, 'sha1')
    text = dump_certificate(FILETYPE_TEXT, self.x509)
    self.assertTrue((b('X509v3    Subject    Key    Identifier:') in text))
