def METHOD_NAME(self):
    """Make sure user can not enter public domain name."""
    form = DomainForm(
        {"domain": settings.PUBLIC_DOMAIN},
        project=self.project,
    )
    self.assertFalse(form.is_valid())
    self.assertEqual(
        form.errors["domain"][0], f"{settings.PUBLIC_DOMAIN} is not a valid domain."
    )
    form2 = DomainForm(
        {"domain": "docs." + settings.PUBLIC_DOMAIN},
        project=self.project,
    )
    self.assertFalse(form2.is_valid())
    self.assertEqual(
        form2.errors["domain"][0],
        f"{settings.PUBLIC_DOMAIN} is not a valid domain.",
    )