Ignore permission checking when counting epics

When showing epics count on group show page, we just
count all epics in the group and its subgroups no matter if
user can see them or not. This is consistent with showing
epic's child counts (where accessibility check is skipped too).

ee/app/finders/epics_finder.rb

@@ -50,7 +50,9 @@ class EpicsFinder < IssuableFinder
     Epic
   end
 
-  def execute
+  def execute(skip_visibility_check: false)
+    @skip_visibility_check = skip_visibility_check
+
     raise ArgumentError, 'group_id argument is missing' unless params[:group_id]
     return Epic.none unless Ability.allowed?(current_user, :read_epic, group)
 
@@ -194,6 +196,7 @@ class EpicsFinder < IssuableFinder
   end
 
   def can_read_all_epics_in_related_groups?(groups)
+    return true if skip_visibility_check?
     return false unless current_user
 
     # If a user is a member of a group, he also inherits access to all subgroups,
@@ -209,4 +212,8 @@ class EpicsFinder < IssuableFinder
     parent = params.fetch(:include_ancestor_groups, false) ? groups.first.root_ancestor : group
     Ability.allowed?(current_user, :read_confidential_epic, parent)
   end
+
+  def skip_visibility_check?
+    @skip_visibility_check && Feature.enabled?(:skip_epic_count_visibility_check, group, default_enabled: true)
+  end
 end

ee/app/helpers/ee/groups_helper.rb

@@ -7,7 +7,7 @@ module EE
     def group_epics_count(state:)
       EpicsFinder
         .new(current_user, group_id: @group.id, state: state)
-        .execute
+        .execute(skip_visibility_check: true)
         .count
     end
 

ee/changelogs/unreleased/epics_count_all.yml

+---
+title: Show count of all epics on group page no matter if user can see them or not.
+merge_request: 35129
+author:
+type: performance

ee/spec/finders/epics_finder_spec.rb

@@ -308,13 +308,32 @@ RSpec.describe EpicsFinder do
           let_it_be(:public_group1) { create(:group, :public, parent: base_group) }
           let_it_be(:public_epic1) { create(:epic, group: public_group1) }
           let_it_be(:public_epic2) { create(:epic, :confidential, group: public_group1) }
+          let(:execute_params) { {} }
 
-          subject { described_class.new(search_user, group_id: base_group.id).execute }
+          subject { described_class.new(search_user, group_id: base_group.id).execute(execute_params) }
 
           it 'returns only public epics' do
             expect(subject).to match_array([base_epic2, public_epic1])
           end
 
+          context 'when skip_visibility_check is true' do
+            let(:execute_params) { { skip_visibility_check: true } }
+
+            it 'returns all epics' do
+              expect(subject).to match_array([base_epic1, base_epic2, private_epic1, private_epic2, public_epic1, public_epic2])
+            end
+
+            context 'when skip_epic_count_visibility_check is disabled' do
+              before do
+                stub_feature_flags(skip_epic_count_visibility_check: false)
+              end
+
+              it 'returns only public epics' do
+                expect(subject).to match_array([base_epic2, public_epic1])
+              end
+            end
+          end
+
           context 'when user is member of ancestor group' do
             before do
               ancestor_group.add_developer(search_user)

ee/spec/helpers/ee/groups_helper_spec.rb

@@ -19,17 +19,33 @@ RSpec.describe GroupsHelper do
   describe '#group_epics_count' do
     before do
       stub_licensed_features(epics: true)
-
-      create_list(:epic, 3, :opened, group: group)
-      create_list(:epic, 2, :closed, group: group)
     end
 
-    it 'returns open epics count' do
-      expect(helper.group_epics_count(state: 'opened')).to eq(3)
+    describe 'filtering by state' do
+      before do
+        create_list(:epic, 3, :opened, group: group)
+        create_list(:epic, 2, :closed, group: group)
+      end
+
+      it 'returns open epics count' do
+        expect(helper.group_epics_count(state: 'opened')).to eq(3)
+      end
+
+      it 'returns closed epics count' do
+        expect(helper.group_epics_count(state: 'closed')).to eq(2)
+      end
     end
 
-    it 'returns closed epics count' do
-      expect(helper.group_epics_count(state: 'closed')).to eq(2)
+    it 'counts also epics from subgroups not visible to user' do
+      parent_group = create(:group, :public)
+      subgroup = create(:group, :private, parent: parent_group)
+      create(:epic, :opened, group: parent_group)
+      create(:epic, :opened, group: subgroup)
+      helper.instance_variable_set(:@group, parent_group)
+
+      expect(Ability.allowed?(owner, :read_epic, parent_group)).to be_truthy
+      expect(Ability.allowed?(owner, :read_epic, subgroup)).to be_falsey
+      expect(helper.group_epics_count(state: 'opened')).to eq(2)
     end
   end