def METHOD_NAME(self, mock_current_user):
    """Assert decorated functions return HTTP 401 when no user is logged in."""
    mock_current_user.is_authenticated = False
    error_details = {
        "error": "authentication_required",
        "error_description": "Authentication is required to access this API.",
    }
    expected_response = (error_details, 401, {"WWW-Authenticate": "Token"})
    @authentication.require_token
    def test_func():
        return "This should not happen!"
    self.assertEqual(expected_response, test_func())