Add support for Enum inheritance

graphene/types/enum.py

@@ -1,4 +1,5 @@
 from enum import Enum as PyEnum
+from typing import Iterable, Type, Optional
 
 from graphene.utils.subclass_with_meta import SubclassWithMeta_Meta
 
@@ -18,11 +19,18 @@ def eq_enum(self, other):
 class EnumOptions(BaseOptions):
     enum = None  # type: Enum
     deprecation_reason = None
+    enums = ()  # type: Iterable[Type[Enum]]
 
 
 class EnumMeta(SubclassWithMeta_Meta):
     def __new__(cls, name_, bases, classdict, **options):
-        enum_members = dict(classdict, __eq__=eq_enum)
+        enum_members = dict(__eq__=eq_enum)
+        meta = classdict.get("Meta", None)  # type: Optional[EnumOptions]
+        if meta and hasattr(meta, 'enums'):
+            for enum in meta.enums:
+                enum_members.update(enum.as_dict())
+        enum_members.update(classdict)
+
         # We remove the Meta attribute from the class to not collide
         # with the enum values.
         enum_members.pop("Meta", None)
@@ -106,3 +114,10 @@ def get_type(cls):
         is mounted (as a Field, InputField or Argument)
         """
         return cls
+
+    @classmethod
+    def as_dict(cls):
+        return {
+            enum_meta.name: enum_meta.value
+            for _, enum_meta in cls._meta.enum.__members__.items()
+        }

graphene/types/tests/test_enum.py

@@ -471,3 +471,77 @@ class Query(ObjectType):
     assert result.data == {"createPaint": {"color": "RED"}}
 
     assert color_input_value == RGB.RED
+
+
+def test_enum_inheritance():
+    class ParentRGB(Enum):
+        RED = 1
+
+    class ChildRGB(Enum):
+        BLUE = 2
+
+        class Meta:
+            enums = (ParentRGB,)
+
+    class Query(ObjectType):
+        color = ChildRGB(required=True)
+
+    schema = Schema(query=Query)
+    assert str(schema) == dedent(
+        '''\
+        type Query {
+          color: ChildRGB!
+        }
+
+        enum ChildRGB {
+          RED
+          BLUE
+        }
+    '''
+    )
+
+
+def test_multiple_enum_inheritance():
+    class Parent1RGB(Enum):
+        RED = 1
+
+    class Parent2RGB(Enum):
+        BLUE = 2
+
+    class ChildRGB(Enum):
+        GREEN = 3
+
+        class Meta:
+            enums = (Parent1RGB, Parent2RGB,)
+
+    class Query(ObjectType):
+        color = ChildRGB(required=True)
+
+    schema = Schema(query=Query)
+    assert str(schema) == dedent(
+        '''\
+        type Query {
+          color: ChildRGB!
+        }
+
+        enum ChildRGB {
+          RED
+          BLUE
+          GREEN
+        }
+    '''
+    )
+
+
+def test_override_enum_inheritance():
+    class ParentRGB(Enum):
+        RED = 1
+        BLUE = 2
+
+    class ChildRGB(Enum):
+        BLUE = 3
+
+        class Meta:
+            enums = (ParentRGB,)
+
+    assert ChildRGB.get(3) != ParentRGB.BLUE