From 0e907899f4ef0c6ffe0fc70a8ef4fef924069eea Mon Sep 17 00:00:00 2001
From: Janosh Riebesell <janosh.riebesell@gmail.com>
Date: Thu, 8 Aug 2024 19:38:18 -0400
Subject: [PATCH] fix print in assert msg returning None, so empty msg

---
 src/pymatgen/core/periodic_table.py                | 4 ++--
 src/pymatgen/io/vasp/inputs.py                     | 6 ++----
 src/pymatgen/transformations/transformation_abc.py | 5 ++---
 src/pymatgen/util/io_utils.py                      | 6 +++---
 tests/core/test_periodic_table.py                  | 6 +++---
 5 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/src/pymatgen/core/periodic_table.py b/src/pymatgen/core/periodic_table.py
index d6992dc3c15..3d465f5eeda 100644
--- a/src/pymatgen/core/periodic_table.py
+++ b/src/pymatgen/core/periodic_table.py
@@ -476,7 +476,7 @@ def parse_orbital(orb_str):
     @property
     def n_electrons(self) -> int:
         """Total number of electrons in the Element."""
-        return sum([t[-1] for t in self.full_electronic_structure])
+        return sum(t[-1] for t in self.full_electronic_structure)
 
     @property
     def valence(self) -> tuple[int | np.nan, int]:
@@ -1180,7 +1180,7 @@ def parse_orbital(orb_str):
     @property
     def n_electrons(self) -> int:
         """Total number of electrons in the Species."""
-        return sum([t[-1] for t in self.full_electronic_structure])
+        return sum(t[-1] for t in self.full_electronic_structure)
 
     # NOTE - copied exactly from Element. Refactoring / inheritance may improve
     # robustness
diff --git a/src/pymatgen/io/vasp/inputs.py b/src/pymatgen/io/vasp/inputs.py
index 9875b1616e1..351dbdcaefd 100644
--- a/src/pymatgen/io/vasp/inputs.py
+++ b/src/pymatgen/io/vasp/inputs.py
@@ -1465,10 +1465,8 @@ def automatic_linemode(cls, divisions: int, ibz: HighSymmKpath) -> Self:
             kpoints.append(ibz.kpath["kpoints"][path[0]])
             labels.append(path[0])
             for i in range(1, len(path) - 1):
-                kpoints.append(ibz.kpath["kpoints"][path[i]])
-                labels.append(path[i])
-                kpoints.append(ibz.kpath["kpoints"][path[i]])
-                labels.append(path[i])
+                kpoints += [ibz.kpath["kpoints"][path[i]]] * 2
+                labels += [path[i]] * 2
 
             kpoints.append(ibz.kpath["kpoints"][path[-1]])
             labels.append(path[-1])
diff --git a/src/pymatgen/transformations/transformation_abc.py b/src/pymatgen/transformations/transformation_abc.py
index 1ed44ac4faf..59a4163345b 100644
--- a/src/pymatgen/transformations/transformation_abc.py
+++ b/src/pymatgen/transformations/transformation_abc.py
@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 import abc
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 from monty.json import MSONable
 
@@ -22,7 +22,7 @@ class AbstractTransformation(MSONable, abc.ABC):
     """Abstract transformation class."""
 
     @abc.abstractmethod
-    def apply_transformation(self, structure: Structure):
+    def apply_transformation(self, structure: Structure) -> Structure | list[dict[str, Any]]:
         """Apply the transformation to a structure. Depending on whether a
         transformation is one-to-many, there may be an option to return a
         ranked list of structures.
@@ -46,7 +46,6 @@ def apply_transformation(self, structure: Structure):
             be stored in the transformation_parameters dictionary in the
             transmuted structure class.
         """
-        return
 
     @property
     def inverse(self) -> AbstractTransformation | None:
diff --git a/src/pymatgen/util/io_utils.py b/src/pymatgen/util/io_utils.py
index 3fc6074841f..47e543bbf89 100644
--- a/src/pymatgen/util/io_utils.py
+++ b/src/pymatgen/util/io_utils.py
@@ -16,7 +16,7 @@
 __date__ = "Sep 23, 2011"
 
 
-def clean_lines(string_list, remove_empty_lines=True):
+def clean_lines(string_list, remove_empty_lines=True) -> list[str]:
     """Strips whitespace, carriage returns and empty lines from a list of strings.
 
     Args:
@@ -24,8 +24,8 @@ def clean_lines(string_list, remove_empty_lines=True):
         remove_empty_lines: Set to True to skip lines which are empty after
             stripping.
 
-    Returns:
-        List of clean strings with no whitespaces.
+    Yields:
+        list: clean strings with no whitespaces.
     """
     for s in string_list:
         clean_s = s
diff --git a/tests/core/test_periodic_table.py b/tests/core/test_periodic_table.py
index d350b2596a7..88a6fbcabfc 100644
--- a/tests/core/test_periodic_table.py
+++ b/tests/core/test_periodic_table.py
@@ -680,9 +680,9 @@ def test_species_electronic_structure(self):
             for ox in el.common_oxidation_states:
                 if str(el) == "H" and ox == 1:
                     continue
-                n_electron_el = sum([orb[-1] for orb in el.full_electronic_structure])
-                n_electron_sp = sum([orb[-1] for orb in Species(el, ox).full_electronic_structure])
-                assert n_electron_el - n_electron_sp == ox, print(f"Failure for {el} {ox}")
+                n_electron_el = sum(orb[-1] for orb in el.full_electronic_structure)
+                n_electron_sp = sum(orb[-1] for orb in Species(el, ox).full_electronic_structure)
+                assert n_electron_el - n_electron_sp == ox, f"Failure for {el} {ox}"
 
 
 def test_get_el_sp():