Use factories to create objects in production

app/services/group_stage_service.rb

@@ -1,4 +1,6 @@
 # frozen_string_literal: true
+require 'factory_bot'
+FactoryBot.definition_file_paths = %w(../../spec/factories)
 
 class GroupStageService
   def self.generate_group_stage(groups)
@@ -8,11 +10,11 @@ class GroupStageService
     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))
-    Stage.new level: -1, groups: groups
+    FactoryBot.create(:group_stage, groups: groups)
   end
 
   def self.get_group_object_from(team_array)
-    Group.new matches: generate_all_matches_between(team_array)
+    FactoryBot.create(:group, matches: generate_all_matches_between(team_array))
   end
 
   def self.generate_all_matches_between(teams)