add basic unit test for initalizing CoupledOperator

tests/unit_tests/test_deplete_coupled_operator.py

@@ -0,0 +1,55 @@
+"""Basic unit tests for openmc.deplete.CoupledOperator instantiation
+
+"""
+
+from pathlib import Path
+
+import pytest
+from openmc.deplete import CoupledOperator
+import openmc
+import numpy as np
+
+CHAIN_PATH = Path(__file__).parents[1] / "chain_simple.xml"
+
+@pytest.fixture(scope="module")
+def model():
+    fuel = openmc.Material(name="uo2")
+    fuel.add_element("U", 1, percent_type="ao", enrichment=4.25)
+    fuel.add_element("O", 2)
+    fuel.set_density("g/cc", 10.4)
+
+    clad = openmc.Material(name="clad")
+    clad.add_element("Zr", 1)
+    clad.set_density("g/cc", 6)
+
+    water = openmc.Material(name="water")
+    water.add_element("O", 1)
+    water.add_element("H", 2)
+    water.set_density("g/cc", 1.0)
+    water.add_s_alpha_beta("c_H_in_H2O")
+
+    radii = [0.42, 0.45]
+    fuel.volume = np.pi * radii[0] ** 2
+    clad.volume = np.pi * (radii[1]**2 - radii[0]**2)
+    water.volume = 1.24**2 - (np.pi * radii[1]**2)
+
+    materials = openmc.Materials([fuel, clad, water])
+
+    pin_surfaces = [openmc.ZCylinder(r=r) for r in radii]
+    pin_univ = openmc.model.pin(pin_surfaces, materials)
+    bound_box = openmc.rectangular_prism(1.24, 1.24, boundary_type="reflective")
+    root_cell = openmc.Cell(fill=pin_univ, region=bound_box)
+    geometry = openmc.Geometry([root_cell])
+
+    settings = openmc.Settings()
+    settings.particles = 1000
+    settings.inactive = 10
+    settings.batches = 50
+
+    return openmc.Model(geometry, materials, settings)
+
+def test_operator_init(model):
+    """The test uses a temporary dummy chain. This file will be removed
+    at the end of the test, and only contains a depletion_chain node."""
+
+    CoupledOperator(model, CHAIN_PATH)