Remove _OS_METHODS variable to make it easier to add custom methods

Having _OS_METHODS meant we couldn't do `_OS_MODULE.METHODS += (MyMethod,)` and that users would have
to update the variable in multiple places. Now, we just access the methods via _OS_MODULE and the user
only has to change it in one place

screen_brightness_control/__init__.py

@@ -4,7 +4,6 @@
 import time
 import traceback
 from dataclasses import dataclass, field
-from types import ModuleType
 from typing import Callable, Any, Dict, List, Optional, Tuple, Type, Union, FrozenSet, ClassVar
 from ._version import __author__, __version__  # noqa: F401
 from .exceptions import NoValidDisplayError, format_exc
@@ -320,7 +319,7 @@ def get_methods(name: Optional[str] = None) -> Dict[str, Type[BrightnessMethod]]
             print('Associated monitors:', sbc.list_monitors(method=method_name))
         ```
     '''
-    methods = {i.__name__.lower(): i for i in _OS_METHODS}
+    methods: Dict[str, type[BrightnessMethod]] = {i.__name__.lower(): i for i in _OS_MODULE.METHODS}
 
     if name is None:
         return methods
@@ -366,7 +365,7 @@ class Display():
     '''The serial number of the display or (if serial is not available) an ID assigned by the OS'''
 
     _logger: logging.Logger = field(init=False, repr=False)
-    _fade_thread_dict: ClassVar[Dict[FrozenSet[Tuple[Any, Any]], threading.Thread]] = {}
+    _fade_thread_dict: ClassVar[Dict[FrozenSet[Any], threading.Thread]] = {}
     '''A dictionary mapping display identifiers to latest fade threads for stopping fades.'''
 
     def __post_init__(self):
@@ -761,16 +760,12 @@ def __brightness(
     raise ScreenBrightnessError(msg)
 
 
-_OS_MODULE: ModuleType
-_OS_METHODS: Tuple[Type[BrightnessMethod], ...]
 if platform.system() == 'Windows':
     from . import windows
     _OS_MODULE = windows
-    _OS_METHODS = windows.METHODS
 elif platform.system() == 'Linux':
     from . import linux
     _OS_MODULE = linux
-    _OS_METHODS = linux.METHODS
 else:
     _logger.warning(
         f'package imported on unsupported platform ({platform.system()})')

tests/conftest.py

@@ -17,7 +17,6 @@
 @pytest.fixture(autouse=True)
 def mock_os_module(monkeypatch: pytest.MonkeyPatch):
     monkeypatch.setattr(sbc, '_OS_MODULE', os_module_mock)
-    monkeypatch.setattr(sbc, '_OS_METHODS', os_module_mock.METHODS)
     return os_module_mock
 
 

tests/test_init.py

@@ -196,7 +196,7 @@ def test_returns_dict_of_brightness_methods(self, subtests):
         methods = sbc.get_methods()
         assert isinstance(methods, dict)
         # check all methods included
-        assert tuple(methods.values()) == sbc._OS_METHODS
+        assert tuple(methods.values()) == sbc._OS_MODULE.METHODS
         # check names match up
         for name, method_class in methods.items():
             with subtests.test(method=name):
@@ -206,7 +206,7 @@ def test_returns_dict_of_brightness_methods(self, subtests):
     class TestNameKwarg:
         def test_non_str_raises_type_error(self):
             with pytest.raises(TypeError, match=r'name must be of type str.*'):
-                sbc.get_methods(sbc._OS_METHODS[0])  # type: ignore
+                sbc.get_methods(sbc._OS_MODULE.METHODS[0])  # type: ignore
 
         def test_raises_value_error_on_invalid_lookup(self):
             with pytest.raises(ValueError, match=r'invalid method.*'):