add test

Author: bckohan

src/polymorphic/admin/inlines.py

@@ -84,7 +84,7 @@ def get_child_inlines(self):
         This should return a list of tuples, exactly like
         :attr:`child_inlines` is.
         """
-        return self.child_inlines or ()
+        return self.child_inlines or []
 
     def get_child_inline_instances(self):
         """

src/polymorphic/tests/admin.py

@@ -1,3 +1,4 @@
+from inspect import isclass
 from django.contrib.admin import register, ModelAdmin, site as admin_site
 from polymorphic.admin import (
     StackedPolymorphicInline,
@@ -35,18 +36,22 @@ class PlainAAdmin(ModelAdmin):
     search_fields = ["field1"]
 
 
-class InlineModelAChild(StackedPolymorphicInline.Child):
+class Inline(StackedPolymorphicInline):
     model = InlineModelA
 
+    def get_child_inlines(self):
+        return [
+            child
+            for child in self.__class__.__dict__.values()
+            if isclass(child) and issubclass(child, StackedPolymorphicInline.Child)
+        ]
 
-class InlineModelBChild(StackedPolymorphicInline.Child):
-    model = InlineModelB
-    autocomplete_fields = ["plain_a"]
-
+    class InlineModelAChild(StackedPolymorphicInline.Child):
+        model = InlineModelA
 
-class Inline(StackedPolymorphicInline):
-    model = InlineModelA
-    child_inlines = (InlineModelAChild, InlineModelBChild)
+    class InlineModelBChild(StackedPolymorphicInline.Child):
+        model = InlineModelB
+        autocomplete_fields = ["plain_a"]
 
 
 @register(InlineParent)