Logged out users can view public group epic boards

Previously, an exception would be thrown when a user was logged out but
tried to view epic boards on a public group when none existed. This
change creates a default epic board so long as the user is authorized to
view the group.

Changelog: fixed
EE: true

ee/app/services/boards/epic_boards/create_service.rb

@@ -20,7 +20,7 @@ module Boards
       def execute
         super.tap do |response|
           if response.success?
-            track_usage_event(:g_project_management_users_creating_epic_boards, current_user.id)
+            track_usage_event(:g_project_management_users_creating_epic_boards, current_user&.id)
           end
         end
       end

ee/spec/controllers/groups/epic_boards_controller_spec.rb

@@ -75,6 +75,24 @@ RSpec.describe Groups::EpicBoardsController do
       end
     end
 
+    context 'with non-logged-in user and public group' do
+      let_it_be(:group) { create(:group, :public) }
+
+      before do
+        sign_out(user)
+      end
+
+      it 'creates a new board when group does not have one' do
+        expect { list_boards }.to change(group.epic_boards, :count).by(1)
+      end
+
+      it 'returns a 200 response' do
+        list_boards
+
+        expect(response).to have_gitlab_http_status(:ok)
+      end
+    end
+
     context 'json request' do
       it 'is not supported' do
         list_boards(format: :json)

ee/spec/services/boards/epic_boards/create_service_spec.rb

@@ -14,11 +14,22 @@ RSpec.describe Boards::EpicBoards::CreateService, services: true do
   context 'create epic board' do
     it_behaves_like 'create a board', :epic_boards
 
-    it 'tracks epic board creation' do
-      expect(Gitlab::UsageDataCounters::HLLRedisCounter)
-        .to receive(:track_event).with('g_project_management_users_creating_epic_boards', values: user.id)
+    context 'when logged in' do
+      it 'tracks epic board creation' do
+        expect(Gitlab::UsageDataCounters::HLLRedisCounter)
+          .to receive(:track_event).with('g_project_management_users_creating_epic_boards', values: user.id)
 
-      described_class.new(parent, user).execute
+        described_class.new(parent, user).execute
+      end
+    end
+
+    context 'when not logged in' do
+      it 'tracks epic board creation' do
+        expect(Gitlab::UsageDataCounters::HLLRedisCounter)
+          .to receive(:track_event).with('g_project_management_users_creating_epic_boards', values: nil)
+
+        described_class.new(parent, nil).execute
+      end
     end
   end
 end