Don't allow setitem on Registry subclasses

autoregistry/_registry.py

@@ -13,6 +13,7 @@
     InvalidNameError,
     KeyCollisionError,
     ModuleAliasError,
+    RegistryError,
 )
 
 
@@ -146,7 +147,10 @@ def __getitem__(self, key: str) -> Type:
         return self.__registry__.config.getitem(self.__registry__, key)
 
     def __setitem__(self, key: str, value: Any):
-        self.__registry__.register(value, key, root=True)
+        if type(self) is RegistryDecorator:
+            self.__registry__.register(value, key, root=True)
+        else:
+            raise RegistryError("Cannot directly setitem on a Registry subclass.")
 
     def __iter__(self) -> Generator[str, None, None]:
         yield from self.__registry__

tests/test_classes.py

@@ -1,6 +1,7 @@
 import pytest
 from common import construct_pokemon_classes
 
+import autoregistry
 from autoregistry import Registry
 
 
@@ -81,6 +82,19 @@ def test_defaults_get():
     assert Pokemon.get("foo", Charmander) == Charmander
 
 
+def test_classes_setitem_exception():
+    """Don't allow setting items for a Registry subclass since it breaks the hierarchy."""
+
+    class Foo(Registry):
+        pass
+
+    def bar():
+        pass
+
+    with pytest.raises(autoregistry.RegistryError):
+        Foo["bar"] = bar
+
+
 def test_multiple_inheritence_last():
     class Foo:
         pass