Add advancing teams into tournaments show endpoint

app/controllers/tournaments_controller.rb

@@ -29,7 +29,7 @@ class TournamentsController < ApplicationController
     if show_params.fetch(:simple, 'false') == 'true'
       render json: @tournament, serializer: SimpleTournamentSerializer
     else
-      render json: @tournament, include: '**'
+      render json: @tournament.as_json(methods: :teams_advancing_from_group_stage)
     end
   end
 

app/models/tournament.rb

@@ -20,6 +20,18 @@ class Tournament < ApplicationRecord
     [stages.map(&:matches), stages.map { |s| s.groups.map(&:matches) }].flatten
   end
 
+  def teams_advancing_from_group_stage
+    group_stage = self.group_stage
+    return [] if group_stage.nil?
+
+    GroupStageService.get_advancing_teams(group_stage)
+  end
+
+  def group_stage
+    # get the stage with level -1 (group stage)
+    stages.find_by(level: -1)
+  end
+
   private
 
   def generate_code

spec/controllers/tournaments_controller_spec.rb

@@ -109,6 +109,20 @@ RSpec.describe TournamentsController, type: :controller do
         body = deserialize_response response
         expect(body[:stages]).to be_nil
         expect(body[:teams]).to be_nil
+        expect(body[:advancing_teams]).to be_nil
+      end
+    end
+    context 'on a group stage tournament' do
+      before do
+        @group_stage_tournament = create(:group_stage_tournament)
+      end
+
+      it 'includes advancing teams' do
+        get :show, params: { id: @group_stage_tournament.to_param }
+        body = deserialize_response response
+        advancing_teams = body[:teams_advancing_from_group_stage]
+        expected_advancing_teams = GroupStageService.get_advancing_teams(@group_stage_tournament.group_stage)
+        expect(advancing_teams).to match_array(expected_advancing_teams)
       end
     end
   end