'Trying to unsubscribe an invalid user from a stream fails gracefully.'

def test_remove_invalid_user(self):

    user_profile = self.example_user('hamlet')
    admin_email = user_profile.email
    self.login(admin_email)
    do_change_is_admin(user_profile, True)
    stream_name = u'h\xfcmb\xfc\u01f5'
    self.make_stream(stream_name)
    result = self.client_delete('/json/users/me/subscriptions', {'subscriptions': ujson.dumps([stream_name]), 'principals': ujson.dumps(['baduser@zulip.com'])})
    self.assert_json_error(result, "User    not    authorized    to    execute    queries    on    behalf    of    'baduser@zulip.com'", status_code=403)
