Add issues filter for any epic

ee/app/finders/ee/issues_finder.rb

@@ -55,6 +55,8 @@ module EE
 
       if params.filter_by_no_epic?
         items.no_epic
+      elsif params.filter_by_any_epic?
+        items.any_epic
       else
         items.in_epics(params.epics)
       end

ee/app/finders/ee/issues_finder/params.rb

@@ -14,6 +14,10 @@ module EE
         params[:epic_id].to_s.downcase == ::IssuableFinder::Params::FILTER_NONE
       end
 
+      def filter_by_any_epic?
+        params[:epic_id].to_s.downcase == ::IssuableFinder::Params::FILTER_ANY
+      end
+
       def weights?
         params[:weight].present? && params[:weight] != ::Issue::WEIGHT_ALL
       end

ee/app/models/ee/issue.rb

@@ -21,6 +21,7 @@ module EE
       scope :order_weight_asc, -> { reorder ::Gitlab::Database.nulls_last_order('weight') }
       scope :service_desk, -> { where(author: ::User.support_bot) }
       scope :no_epic, -> { left_outer_joins(:epic_issue).where(epic_issues: { epic_id: nil }) }
+      scope :any_epic, -> { joins(:epic_issue) }
       scope :in_epics, ->(epics) do
         issue_ids = EpicIssue.where(epic_id: epics).select(:issue_id)
         id_in(issue_ids)

ee/changelogs/unreleased/215657-searching-issues-with-epic-any-doesn-t-return-anything.yml

+---
+title: Fix issues search to include the epic filter ANY
+merge_request: 31614
+author:
+type: fixed

ee/spec/finders/issues_finder_spec.rb

@@ -113,6 +113,14 @@ describe IssuesFinder do
             end
           end
         end
+
+        context 'filter issues with any epic' do
+          let(:params) { { epic_id: ::IssuableFinder::Params::FILTER_ANY } }
+
+          it 'returns filtered issues' do
+            expect(issues).to contain_exactly(issue_1, issue_2, issue_subepic)
+          end
+        end
       end
     end
   end

ee/spec/models/issue_spec.rb

@@ -128,6 +128,13 @@ describe Issue do
         end
       end
 
+      describe '.any_epic' do
+        it 'returns only issues with an epic assigned' do
+          expect(described_class.count).to eq 3
+          expect(described_class.any_epic).to eq [epic_issue1.issue, epic_issue2.issue]
+        end
+      end
+
       describe '.in_epics' do
         it 'returns only issues in selected epics' do
           expect(described_class.count).to eq 3