Core: fix settings API for removal of Python 3.8, 3.9 (#4280)

* Core: fix settings API for removal of Python 3.8, 3.9

This is fixing 2 problems:
- The `World` class has the annotation:
  `settings: ClassVar[Optional["Group"]]`
  so `MyWorld.settings` should not raise an exception like it does for some worlds.
  With the `Optional` there, it looks like it should return `None` for the worlds that don't use it. So that's what I changed it to.

- `Group.update` had some code that required `typing.Union` instead of the Python 3.10 `|` for unions.

added unit test for this fix
added change in Zillion that I used to discover this problem and used it to test the test

* fix copy-pasted stuff

* tuple instead of set

Co-authored-by: black-sliver <59490463+black-sliver@users.noreply.github.com>

---------

Co-authored-by: black-sliver <59490463+black-sliver@users.noreply.github.com>

settings.py

@@ -7,6 +7,7 @@ import os
 import os.path
 import shutil
 import sys
+import types
 import typing
 import warnings
 from enum import IntEnum
@@ -162,8 +163,13 @@ class Group:
             else:
                 # assign value, try to upcast to type hint
                 annotation = self.get_type_hints().get(k, None)
-                candidates = [] if annotation is None else \
-                    typing.get_args(annotation) if typing.get_origin(annotation) is Union else [annotation]
+                candidates = (
+                    [] if annotation is None else (
+                        typing.get_args(annotation)
+                        if typing.get_origin(annotation) in (Union, types.UnionType)
+                        else [annotation]
+                    )
+                )
                 none_type = type(None)
                 for cls in candidates:
                     assert isinstance(cls, type), f"{self.__class__.__name__}.{k}: type {cls} not supported in settings"

test/general/test_settings.py

@@ -0,0 +1,16 @@
+from unittest import TestCase
+
+from settings import Group
+from worlds.AutoWorld import AutoWorldRegister
+
+
+class TestSettings(TestCase):
+    def test_settings_can_update(self) -> None:
+        """
+        Test that world settings can update.
+        """
+        for game_name, world_type in AutoWorldRegister.world_types.items():
+            with self.subTest(game=game_name):
+                if world_type.settings is not None:
+                    assert isinstance(world_type.settings, Group)
+                    world_type.settings.update({})  # a previous bug had a crash in this call to update

worlds/AutoWorld.py

@@ -33,7 +33,10 @@ class AutoWorldRegister(type):
         # lazy loading + caching to minimize runtime cost
         if cls.__settings is None:
             from settings import get_settings
-            cls.__settings = get_settings()[cls.settings_key]
+            try:
+                cls.__settings = get_settings()[cls.settings_key]
+            except AttributeError:
+                return None
         return cls.__settings
 
     def __new__(mcs, name: str, bases: Tuple[type, ...], dct: Dict[str, Any]) -> AutoWorldRegister:

worlds/zillion/__init__.py

@@ -47,7 +47,7 @@ class ZillionSettings(settings.Group):
         """
 
     rom_file: RomFile = RomFile(RomFile.copy_to)
-    rom_start: typing.Union[RomStart, bool] = RomStart("retroarch")
+    rom_start: RomStart | bool = RomStart("retroarch")
 
 
 class ZillionWebWorld(WebWorld):