Fix input_path resolving empty filenames to cwd

openmc/utility_funcs.py

@@ -69,6 +69,14 @@ def input_path(filename: PathLike) -> Path:
         Path object
 
     """
+    # An empty filename represents the absence of a path (e.g., a mesh or
+    # DAGMC universe read back from a summary/statepoint file that was never
+    # written with a source file) and should not be resolved to the current
+    # working directory.
+    filename = os.fspath(filename)
+    if not filename:
+        return Path(filename)
+
     if openmc.config['resolve_paths']:
         path = Path(filename)
         xml_dir = _XML_INPUT_PATH.get()

tests/unit_tests/test_mesh.py

@@ -470,7 +470,8 @@ def test_umesh_from_hdf5_without_filename(run_in_tmpdir):
         group['connectivity'] = np.zeros((1, 8), dtype=int)
         group['element_types'] = [0]
 
-        mesh = openmc.MeshBase.from_hdf5(group)
+        with openmc.config.patch('resolve_paths', True):
+            mesh = openmc.MeshBase.from_hdf5(group)
 
     assert mesh.filename == Path()
     assert mesh.has_statepoint_data

tests/unit_tests/test_universe.py

@@ -198,7 +198,8 @@ def test_dagmc_universe_from_hdf5_without_filename(run_in_tmpdir):
         group.attrs['auto_mat_ids'] = 1
         group.attrs['length_multiplier'] = 1.0
 
-        univ = openmc.DAGMCUniverse.from_hdf5(group)
+        with openmc.config.patch('resolve_paths', True):
+            univ = openmc.DAGMCUniverse.from_hdf5(group)
 
     assert univ.id == 1
     assert univ.filename == Path()

tests/unit_tests/test_utility_funcs.py

@@ -0,0 +1,20 @@
+from pathlib import Path
+
+import openmc
+from openmc.utility_funcs import input_path
+
+
+def test_input_path_empty_not_resolved():
+    """An empty filename represents "no file" (e.g., an in-memory mesh or
+    DAGMC universe read back from a summary/statepoint that was never
+    written with a source file, see UnstructuredMesh.from_hdf5 and
+    DAGMCUniverse.from_hdf5) and should stay empty rather than being
+    resolved to the current working directory."""
+    with openmc.config.patch('resolve_paths', True):
+        assert input_path('') == Path()
+
+
+def test_input_path_nonempty_resolved(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+    with openmc.config.patch('resolve_paths', True):
+        assert input_path('foo.h5') == (tmp_path / 'foo.h5').resolve()

tests/unit_tests/weightwindows/test.py

@@ -1,11 +1,10 @@
 import os
 from itertools import product
+from pathlib import Path
 
 import pytest
-
 import numpy as np
 from uncertainties import ufloat
-
 import openmc
 import openmc.lib
 from openmc.stats import Discrete, Point