1 files changed, 40 insertions, 10 deletions
diff --git a/pint/facets/group/registry.py b/pint/facets/group/registry.py
index 0d35ae0..f130e61 100644
--- a/pint/facets/group/registry.py
+++ b/pint/facets/group/registry.py
@@ -8,20 +8,28 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Generic, Any
 
+from ...compat import TypeAlias
 from ... import errors
 
 if TYPE_CHECKING:
-    from ..._typing import Unit
-
-from ...util import create_class_with_registry
-from ..plain import PlainRegistry, UnitDefinition
+    from ..._typing import Unit, UnitsContainer
+
+from ...util import create_class_with_registry, to_units_container
+from ..plain import (
+    GenericPlainRegistry,
+    UnitDefinition,
+    QuantityT,
+    UnitT,
+)
 from .definitions import GroupDefinition
 from . import objects
 
 
-class GroupRegistry(PlainRegistry):
+class GenericGroupRegistry(
+    Generic[QuantityT, UnitT], GenericPlainRegistry[QuantityT, UnitT]
+):
     """Handle of Groups.
 
     Group units
@@ -34,7 +42,7 @@ class GroupRegistry(PlainRegistry):
     # TODO: Change this to Group: Group to specify class
     # and use introspection to get system class as a way
     # to enjoy typing goodies
-    Group = objects.Group
+    Group = type[objects.Group]
 
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
@@ -46,7 +54,7 @@ class GroupRegistry(PlainRegistry):
     def _init_dynamic_classes(self) -> None:
         """Generate subclasses on the fly and attach them to self"""
         super()._init_dynamic_classes()
-        self.Group = create_class_with_registry(self, self.Group)
+        self.Group = create_class_with_registry(self, objects.Group)
 
     def _after_init(self) -> None:
         """Invoked at the end of ``__init__``.
@@ -113,8 +121,23 @@ class GroupRegistry(PlainRegistry):
 
         return self.Group(name)
 
-    def _get_compatible_units(self, input_units, group) -> frozenset[Unit]:
-        ret = super()._get_compatible_units(input_units, group)
+    def get_compatible_units(
+        self, input_units: UnitsContainer, group: str | None = None
+    ) -> frozenset[Unit]:
+        """ """
+        if group is None:
+            return super().get_compatible_units(input_units)
+
+        input_units = to_units_container(input_units)
+
+        equiv = self._get_compatible_units(input_units, group)
+
+        return frozenset(self.Unit(eq) for eq in equiv)
+
+    def _get_compatible_units(
+        self, input_units: UnitsContainer, group: str | None = None
+    ) -> frozenset[str]:
+        ret = super()._get_compatible_units(input_units)
 
         if not group:
             return ret
@@ -124,3 +147,10 @@ class GroupRegistry(PlainRegistry):
         else:
             raise ValueError("Unknown Group with name '%s'" % group)
         return frozenset(ret & members)
+
+
+class GroupRegistry(
+    GenericGroupRegistry[objects.GroupQuantity[Any], objects.GroupUnit]
+):
+    Quantity: TypeAlias = objects.GroupQuantity[Any]
+    Unit: TypeAlias = objects.GroupUnit