Fix TestPotcar.test_write polluting git repo on failure (#3347)

* improve StructureError msg on species/coord length mismatch

* fix TestPotcar.test_write polluting git repo on failure

pymatgen/core/structure.py

@@ -888,7 +888,7 @@ def __init__(
                 lost when converting to other formats.
         """
         if len(species) != len(coords):
-            raise StructureError("atomic species and fractional coordinates must have same length")
+            raise StructureError(f"{len(species)=} != {len(coords)=}")
 
         self._lattice = lattice if isinstance(lattice, Lattice) else Lattice(lattice)
 

pymatgen/io/vasp/inputs.py

@@ -1804,7 +1804,7 @@ def __init__(self, data, symbol=None):
         has_sh256, hash_check_passed = self.verify_potcar()
         if not has_sh256 and not hash_check_passed:
             warnings.warn(
-                f"POTCAR data with symbol { self.symbol} does not match any VASP "
+                f"POTCAR data with symbol {self.symbol} does not match any VASP "
                 "POTCAR known to pymatgen. There is a possibility your "
                 "POTCAR is corrupted or that the pymatgen database is incomplete.",
                 UnknownPotcarWarning,

tests/core/test_structure.py

@@ -1396,7 +1396,7 @@ def test_set_item(self):
         assert struct.formula == "Si1.25 C0.125"
 
     def test_init_error(self):
-        with pytest.raises(StructureError, match="atomic species and fractional coordinates must have same length"):
+        with pytest.raises(StructureError, match=r"len\(species\)=1 != len\(coords\)=2"):
             Structure(Lattice.cubic(3), ["Si"], [[0, 0, 0], [0.5, 0.5, 0.5]])
 
     def test_from_sites(self):

tests/io/vasp/test_inputs.py

@@ -1096,7 +1096,7 @@ def test_repr(self):
         )
 
 
-class TestPotcar(unittest.TestCase):
+class TestPotcar(PymatgenTest):
     def setUp(self):
         if "PMG_VASP_PSP_DIR" not in SETTINGS:
             SETTINGS["PMG_VASP_PSP_DIR"] = str(TEST_FILES_DIR)
@@ -1125,24 +1125,20 @@ def test_as_from_dict(self):
         assert potcar.symbols == ["Fe", "P", "O"]
 
     def test_write(self):
-        tempfname = Path("POTCAR.testing")
-        self.potcar.write_file(tempfname)
-        p = Potcar.from_file(tempfname)
+        tmp_file = f"{self.tmp_path}/POTCAR.testing"
+        self.potcar.write_file(tmp_file)
+        p = Potcar.from_file(tmp_file)
         assert p.symbols == self.potcar.symbols
 
-        # check line by line
-        with open(self.filepath) as f_ref, open(tempfname) as f_new:
+        with open(self.filepath) as f_ref, open(tmp_file) as f_new:
             ref_potcar = f_ref.readlines()
             new_potcar = f_new.readlines()
 
-        if len(ref_potcar) != len(new_potcar):
-            raise AssertionError("POTCAR file lengths are not equal")
+        assert len(ref_potcar) == len(new_potcar), f"wrong POTCAR line count: {len(ref_potcar)} != {len(new_potcar)}"
 
+        # check line by line
         for line1, line2 in zip(ref_potcar, new_potcar):
-            if line1.strip() != line2.strip():
-                raise AssertionError("POTCAR contents are not")
-
-        tempfname.unlink()
+            assert line1.strip() == line2.strip(), f"wrong POTCAR line: {line1} != {line2}"
 
     def test_set_symbol(self):
         assert self.potcar.symbols == ["Fe", "P", "O"]