fix: require deciders for advancing ties

app/services/group_stage_service.rb

@@ -224,12 +224,11 @@ class GroupStageService
       nil
     end
 
-    def unresolved_tie_crosses_advancing_cutoff?(sorted_group_scores, group_score, advancing_slots)
+    def unresolved_tie_affects_advancing_placements?(sorted_group_scores, group_score, advancing_slots)
       return false if advancing_slots.zero?
 
       cluster = tie_cluster_for(sorted_group_scores, group_score)
-      occupied_slots = (cluster[:start_index] + 1)..(cluster[:end_index] + 1)
+      cluster[:start_index] < advancing_slots
-      occupied_slots.begin <= advancing_slots && occupied_slots.end > advancing_slots
     end
 
     def tie_cluster_for(sorted_group_scores, group_score)
@@ -298,7 +297,7 @@ class GroupStageService
           tied: comparison_reason[:tied],
           needs_decider_match: group_ready_for_decider_check &&
             comparison_reason[:tied] &&
-            unresolved_tie_crosses_advancing_cutoff?(sorted_group_scores, group_score, advancing_slots)
+            unresolved_tie_affects_advancing_placements?(sorted_group_scores, group_score, advancing_slots)
         }
       end
 

spec/controllers/stages_controller_spec.rb

@@ -201,5 +201,41 @@ RSpec.describe StagesController, type: :controller do
         expect(body[:blocking_ties].first[:team_names]).to eq(%w[A B])
       end
     end
+
+    context 'when tied advancing teams still need a decider to fix playoff seeding' do
+      let(:group_stage) do
+        create(:group_stage, tournament: create(:tournament, teams_count: 0), group_count: 0)
+      end
+
+      before do
+        tournament = group_stage.tournament
+        tournament.update!(playoff_teams_amount: 2, instant_finalists_amount: 2, intermediate_round_participants_amount: 0)
+        group = create(:group, stage: group_stage, match_count: 0, number: 1)
+        group_stage.groups = [group]
+        team_a = create(:team, tournament: tournament, name: 'A')
+        team_b = create(:team, tournament: tournament, name: 'B')
+        create(:group_match, group: group, state: :finished).tap do |match|
+          create(:match_score, match: match, team: team_a, points: 2)
+          create(:match_score, match: match, team: team_b, points: 2)
+        end
+        score_a = create(:group_score, group: group, team: team_a, group_points: 7, scored_points: 4, received_points: 1)
+        score_b = create(:group_score, group: group, team: team_b, group_points: 7, scored_points: 4, received_points: 1)
+        GroupStageService.send(:recalculate_position_of_group_scores!, [score_a, score_b]).each(&:save!)
+
+        apply_authentication_headers_for group_stage.owner
+        put :update, params: { id: group_stage.to_param }.merge(finished)
+      end
+
+      it 'returns unprocessable entity' do
+        expect(response).to have_http_status(:unprocessable_entity)
+      end
+
+      it 'returns a helpful decider error' do
+        body = deserialize_response(response)
+        expect(body[:error]).to eq('Playoffs cannot be generated yet because a decider match is required for an advancing place')
+        expect(body[:blocking_ties].size).to eq(1)
+        expect(body[:blocking_ties].first[:team_names]).to eq(%w[A B])
+      end
+    end
   end
 end

spec/services/group_stage_service_spec.rb

@@ -268,7 +268,7 @@ RSpec.describe GroupStageService do
       )
     end
 
-    it 'keeps shared positions and requests a decider only when an unresolved tie crosses the cutoff' do
+    it 'keeps shared positions and requests a decider when an unresolved tie affects advancing placements' do
       tournament.update!(playoff_teams_amount: 1, instant_finalists_amount: 1, intermediate_round_participants_amount: 0)
 
       create(:group_match, group: group, state: :finished).tap do |match|
@@ -300,6 +300,38 @@ RSpec.describe GroupStageService do
       )
     end
 
+    it 'requests a decider when tied teams both advance but their seeding stays unresolved' do
+      tournament.update!(playoff_teams_amount: 2, instant_finalists_amount: 2, intermediate_round_participants_amount: 0)
+
+      create(:group_match, group: group, state: :finished).tap do |match|
+        create(:match_score, match: match, team: team_a, points: 2)
+        create(:match_score, match: match, team: team_b, points: 2)
+      end
+
+      score_a = create(:group_score, group: group, team: team_a, group_points: 7, scored_points: 4, received_points: 1)
+      score_b = create(:group_score, group: group, team: team_b, group_points: 7, scored_points: 4, received_points: 1)
+      score_c = create(:group_score, group: group, team: team_c, group_points: 3, scored_points: 2, received_points: 3)
+      score_d = create(:group_score, group: group, team: team_d, group_points: 0, scored_points: 1, received_points: 7)
+
+      GroupStageService.send(:recalculate_position_of_group_scores!, [score_a, score_b, score_c, score_d]).each(&:save!)
+
+      expect([score_a.position, score_b.position, score_c.position, score_d.position]).to eq([1, 1, 3, 4])
+      expect(GroupStageService.ranking_decision_for(score_a)).to include(
+        resolved_by: 'tie',
+        direct_comparison_result: 'draw',
+        hidden_points_result: 'not_played',
+        tied: true,
+        needs_decider_match: true
+      )
+      expect(GroupStageService.ranking_decision_for(score_b)).to include(
+        resolved_by: 'tie',
+        direct_comparison_result: 'draw',
+        hidden_points_result: 'not_played',
+        tied: true,
+        needs_decider_match: true
+      )
+    end
+
     it 'does not expose unresolved tie metadata while regular matches in the group are still unfinished' do
       tournament.update!(playoff_teams_amount: 1, instant_finalists_amount: 1, intermediate_round_participants_amount: 0)