From 04bee9c49fc95836cd0324992d69deed72aa1e09 Mon Sep 17 00:00:00 2001
From: GuySten <62616591+GuySten@users.noreply.github.com>
Date: Fri, 6 Feb 2026 20:44:16 +0200
Subject: [PATCH] Check that Surface IDs are at least 1 (#3772)

Co-authored-by: Paul Romano <paul.k.romano@gmail.com>
---
 openmc/mixin.py                   | 4 +++-
 openmc/surface.py                 | 1 +
 tests/unit_tests/test_cell.py     | 6 ++++++
 tests/unit_tests/test_material.py | 7 +++++++
 tests/unit_tests/test_surface.py  | 6 ++++++
 tests/unit_tests/test_universe.py | 6 ++++++
 6 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/openmc/mixin.py b/openmc/mixin.py
index 0bc4128b0..28c97bfdd 100644
--- a/openmc/mixin.py
+++ b/openmc/mixin.py
@@ -39,6 +39,8 @@ class IDManagerMixin:
 
     """
 
+    min_id = 0
+
     @property
     def id(self):
         return self._id
@@ -64,7 +66,7 @@ class IDManagerMixin:
         else:
             name = cls.__name__
             cv.check_type(f'{name} ID', uid, Integral)
-            cv.check_greater_than(f'{name} ID', uid, 0, equality=True)
+            cv.check_greater_than(f'{name} ID', uid, cls.min_id, equality=True)
             if uid in cls.used_ids:
                 msg = f'Another {name} instance already exists with id={uid}.'
                 warn(msg, IDWarning)
diff --git a/openmc/surface.py b/openmc/surface.py
index 1fe5fabdf..97aca43b3 100644
--- a/openmc/surface.py
+++ b/openmc/surface.py
@@ -151,6 +151,7 @@ class Surface(IDManagerMixin, ABC):
 
     """
 
+    min_id = 1
     next_id = 1
     used_ids = set()
     _atol = 1.e-12
diff --git a/tests/unit_tests/test_cell.py b/tests/unit_tests/test_cell.py
index 60b205818..2baa59f1b 100644
--- a/tests/unit_tests/test_cell.py
+++ b/tests/unit_tests/test_cell.py
@@ -20,6 +20,12 @@ def test_contains():
     assert (10.0, -4., 2.0) in c
 
 
+def test_id():
+    openmc.Cell(cell_id=0)
+    with pytest.raises(ValueError):
+        openmc.Cell(cell_id=-1)
+
+
 def test_repr(cell_with_lattice):
     cells, mats, univ, lattice = cell_with_lattice
     repr(cells[0])  # cell with distributed materials
diff --git a/tests/unit_tests/test_material.py b/tests/unit_tests/test_material.py
index 764c98d41..0b1b5fce2 100644
--- a/tests/unit_tests/test_material.py
+++ b/tests/unit_tests/test_material.py
@@ -77,6 +77,13 @@ def test_add_components():
     with pytest.raises(ValueError):
         m.add_components({'H1': 1.0}, percent_type = 'oa')
 
+
+def test_id():
+    openmc.Material(material_id=0)
+    with pytest.raises(ValueError):
+        openmc.Material(material_id=-1)
+
+
 def test_nuclides_to_ignore(run_in_tmpdir):
     """Test nuclides_to_ignore when exporting a material to XML"""
     m = openmc.Material()
diff --git a/tests/unit_tests/test_surface.py b/tests/unit_tests/test_surface.py
index e9560223d..aaf591e05 100644
--- a/tests/unit_tests/test_surface.py
+++ b/tests/unit_tests/test_surface.py
@@ -7,6 +7,12 @@ import openmc
 import pytest
 
 
+def test_id():
+    for i in range(-10, 1):
+        with pytest.raises(ValueError):
+            openmc.Plane(a=1, b=2, c=-1, d=3, surface_id=i)
+
+
 def assert_infinite_bb(s):
     ll, ur = (-s).bounding_box
     assert np.all(np.isinf(ll))
diff --git a/tests/unit_tests/test_universe.py b/tests/unit_tests/test_universe.py
index 6fbf1cc38..0955347f7 100644
--- a/tests/unit_tests/test_universe.py
+++ b/tests/unit_tests/test_universe.py
@@ -49,6 +49,12 @@ def test_bounding_box():
     assert_unbounded(u)
 
 
+def test_id():
+    openmc.Universe(universe_id=0)
+    with pytest.raises(ValueError):
+        openmc.Universe(universe_id=-1)
+
+
 def test_plot(run_in_tmpdir, sphere_model):
 
     # model with -inf and inf in the bounding box