Assign number to each group

app/services/group_stage_service.rb

@@ -8,7 +8,7 @@ class GroupStageService
       # raise an error if the average group size is not a whole number
       raise 'Groups need to be equal size' unless (groups.flatten.length.to_f / groups.length.to_f % 1).zero?
 
-      groups = groups.map(&method(:get_group_object_from))
+      groups = groups.map(&method(:get_group_object_from)).each_with_index { |group, i| group.number = i + 1 }
       Stage.new level: -1, groups: groups, state: :in_progress
     end
 

spec/services/group_stage_service_spec.rb

@@ -19,6 +19,13 @@ RSpec.describe GroupStageService do
       expect(prepared_groups_groupstage.state).to eq('in_progress')
     end
 
+    it 'assigns unique numbers to each group' do
+      groups = prepared_groups_groupstage.groups
+      groups.sort_by(&:number).each_with_index do |group, i|
+        expect(group.number).to eq(i + 1)
+      end
+    end
+
     it 'returns a stage object with level -1' do
       expect(prepared_groups_groupstage.level).to be(-1)
     end