def METHOD_NAME(self):
    data = {self.field_name: "192.168.0.1/0", "namespace": self.namespace, "status": self.status}
    data.update(self.extra_data)
    form = self.form_class(data)
    # With the advent of `Prefix.parent`, it's now possible to create a /0 .
    self.assertTrue(form.is_valid())