'signature(value, salt=...) should work'

def test_signature_with_salt(self):

    signer = signing.Signer(u'predictable-secret', salt=u'extra-salt')
    self.assertEqual(signer.signature(u'hello'), signing.base64_hmac((u'extra-salt' + u'signer'), u'hello', u'predictable-secret').decode())
    self.assertNotEqual(signing.Signer(u'predictable-secret', salt=u'one').signature(u'hello'), signing.Signer(u'predictable-secret', salt=u'two').signature(u'hello'))
