Fix teams not associated with created tournament

when choosing a group stage

app/controllers/tournaments_controller.rb

@@ -39,6 +39,8 @@ class TournamentsController < ApplicationController
     if group_stage
       params.require(:playoff_teams_amount)
       groups = organize_teams_in_groups(teams)
+      # associate provided teams with tournament
+      tournament.teams = groups.flatten
       # add groups to tournament
       result = AddGroupStageToTournamentAndSave.call(tournament: tournament, groups: groups)
     else

spec/controllers/tournaments_controller_spec.rb

@@ -195,6 +195,10 @@ RSpec.describe TournamentsController, type: :controller do
               .to eq(create_group_tournament_data[:playoff_teams_amount])
           end
 
+          it 'associates the given teams with the created tournament' do
+            expect(@group_stage_tournament.teams).to match_array(@teams16)
+          end
+
           context 'playoff_teams_amount unacceptable' do
             shared_examples_for 'wrong playoff_teams_amount' do
               it 'fails' do