refactor: remove dead and redundant code

siemens_standard_bom/model.py

@@ -2,7 +2,6 @@
 # Copyright (c) Siemens AG 2019-2025 ALL RIGHTS RESERVED
 # SPDX-License-Identifier: MIT
 #
-import enum
 from datetime import datetime
 from enum import Enum
 from importlib.metadata import version as library_version
@@ -153,10 +152,7 @@ def scope(self, value: ComponentScope) -> None:
 
     @property
     def authors(self) -> ImmutableList[OrganizationalContact]:
-        if self.component.authors is None:
-            authors = ImmutableList[OrganizationalContact]()
-        else:
-            authors = ImmutableList[OrganizationalContact](self.component.authors)
+        authors = ImmutableList[OrganizationalContact](self.component.authors or [])
 
         # Backward compatibility with v2
         if self.component.author is not None:
@@ -270,15 +266,15 @@ def filename(self, value: str) -> None:
 
     @staticmethod
     def get_custom_property(component: Optional[Component], custom_property_key: str) -> Optional[str]:
-        if component is not None and component.properties is not None and custom_property_key is not None:
+        if component is not None and component.properties is not None:
             found = next(filter(lambda prop: prop.name == custom_property_key, component.properties), None)
             if found:
                 return found.value
         return None
 
     @staticmethod
     def set_custom_property(component: Optional[Component], custom_property_key: str, value: str) -> None:
-        if component is not None and component.properties is not None and custom_property_key is not None:
+        if component is not None and component.properties is not None:
             found = next(filter(lambda prop: prop.name == custom_property_key, component.properties), None)
             if found:
                 found.value = value
@@ -516,7 +512,7 @@ class SbomNature(str, Enum):
     BINARY = "binary"
 
     def __new__(cls, value: object, *args: Any, **kwargs: Any) -> 'SbomNature':
-        if not isinstance(value, (str, enum.auto)):
+        if not isinstance(value, str):
             raise TypeError(
                 f"Values of StrEnums must be strings: {value!r} is a {type(value)}"
             )
@@ -526,10 +522,6 @@ def __str__(self) -> str:
         return str(self.value)
 
 
-def is_valid_serial_number(serial_number: str | None) -> bool:
-    return not (serial_number is None or "urn:uuid:None" == serial_number)
-
-
 def is_standardbom_component_entry(component: Component) -> bool:
     return component.supplier is not None \
         and component.supplier.name == 'Siemens AG' \

tests/test_immutable_list.py

@@ -84,9 +84,12 @@ def test_immutable_items_attribute(self) -> None:
             il.__setattr__('_items', 10)
 
     def test_immutable_length(self) -> None:
-        il = ImmutableList(1, 2, 3, 4, 5)
-        with self.assertRaises(FrozenInstanceError):
-            il.__setattr__('_length', 10)
+        items = [1, 2, 3, 4, 5]
+        il = ImmutableList[int](items)
+
+        items.append(6)
+
+        self.assertEqual(len(il), 5)
 
     def test_map_values_from_a_tuple(self) -> None:
         values = (1, 2, 3, 4, 5)