Rename finder param to include_parent_descendants

- Add tests for new finder param
include_parent_descendants

app/finders/groups_finder.rb

@@ -12,7 +12,7 @@
 #     all_available: boolean (defaults to true)
 #     min_access_level: integer
 #     exclude_group_ids: array of integers
-#     include_descendants: boolean (defaults to false)
+#     include_parent_descendants: boolean (defaults to false)
 #
 # Users with full private access can see all groups. The `owned` and `parent`
 # params can be used to restrict the groups that are returned.
@@ -85,8 +85,9 @@ class GroupsFinder < UnionFinder
   def by_parent(groups)
     return groups unless params[:parent]
 
-    if params[:include_descendants]
-      groups.id_in(hierarchy_for_parent(params[:parent]).descendants.pluck(:id))
+    if include_parent_descendants?
+      descendants = Gitlab::ObjectHierarchy.new(Group.where(id: params[:parent])).descendants
+      groups.id_in(descendants.pluck(:id))
     else
       groups.where(parent: params[:parent])
     end
@@ -105,13 +106,11 @@ class GroupsFinder < UnionFinder
     params.fetch(:all_available, true)
   end
 
-  def min_access_level?
-    current_user && params[:min_access_level].present?
+  def include_parent_descendants?
+    params.fetch(:include_parent_descendants, false)
   end
 
-  # rubocop: disable CodeReuse/ActiveRecord
-  def hierarchy_for_parent(parent_group_id)
-    @hierarchy ||= Gitlab::ObjectHierarchy.new(Group.where(id: parent_group_id))
+  def min_access_level?
+    current_user && params[:min_access_level].present?
   end
-  # rubocop: enable CodeReuse/ActiveRecord
 end

lib/api/groups.rb

@@ -33,7 +33,7 @@ module API
           :all_available,
           :custom_attributes,
           :owned, :min_access_level,
-          :include_descendants
+          :include_parent_descendants
         )
 
         find_params[:parent] = if params[:top_level_only]
@@ -322,7 +322,7 @@ module API
         use :with_custom_attributes
       end
       get ":id/descendant_groups" do
-        finder_params = declared_params(include_missing: false).merge(include_descendants: true)
+        finder_params = declared_params(include_missing: false).merge(include_parent_descendants: true)
         groups = find_groups(finder_params, params[:id])
         present_groups params, groups
       end

spec/finders/groups_finder_spec.rb

@@ -161,5 +161,61 @@ RSpec.describe GroupsFinder do
         end
       end
     end
+
+    context 'with include parent group descendants' do
+      let_it_be(:user) { create(:user) }
+      let_it_be(:parent_group) { create(:group, :public) }
+      let_it_be(:public_subgroup) { create(:group, :public, parent: parent_group) }
+      let_it_be(:internal_sub_subgroup) { create(:group, :internal, parent: public_subgroup) }
+      let_it_be(:private_sub_subgroup) { create(:group, :private, parent: public_subgroup) }
+      let_it_be(:public_sub_subgroup) { create(:group, :public, parent: public_subgroup) }
+      let(:params) { { include_parent_descendants: true, parent: parent_group } }
+
+      context 'with nil parent' do
+        it 'returns all accessible groups' do
+          params[:parent] = nil
+          expect(described_class.new(user, params).execute).to contain_exactly(
+            parent_group,
+            public_subgroup,
+            internal_sub_subgroup,
+            public_sub_subgroup
+          )
+        end
+      end
+
+      context 'without a user' do
+        it 'only returns the group public descendants' do
+          expect(described_class.new(nil, params).execute).to contain_exactly(
+            public_subgroup,
+            public_sub_subgroup
+          )
+        end
+      end
+
+      context 'when a user is present' do
+        it 'returns the group public and internal descendants' do
+          expect(described_class.new(user, params).execute).to contain_exactly(
+            public_subgroup,
+            public_sub_subgroup,
+            internal_sub_subgroup
+          )
+        end
+      end
+
+      context 'when a parent group member is present' do
+        before do
+          parent_group.add_developer(user)
+        end
+
+        it 'returns all group descendants' do
+          expect(described_class.new(user, params).execute).to contain_exactly(
+            public_subgroup,
+            public_sub_subgroup,
+            internal_sub_subgroup,
+            private_sub_subgroup
+          )
+        end
+      end
+    end
   end
 end