Update Tables::Distribution#save! to consider that the distribution may already be persisted

app/models/seat.rb

@@ -29,5 +29,5 @@
 class Seat < ApplicationRecord
   acts_as_tenant :wedding
   belongs_to :guest
-  belongs_to :table_arrangement
+  belongs_to :tables_arrangement
 end

app/services/tables/distribution.rb

@@ -12,13 +12,14 @@ module Tables
       end
     end
 
-    attr_accessor :tables, :min_per_table, :max_per_table, :hierarchy
+    attr_accessor :tables, :min_per_table, :max_per_table, :hierarchy, :tables_arrangement_id
 
-    def initialize(min_per_table:, max_per_table:, hierarchy: AffinityGroupsHierarchy.new)
+    def initialize(min_per_table:, max_per_table:, hierarchy: AffinityGroupsHierarchy.new, tables_arrangement_id: nil)
       @min_per_table = min_per_table
       @max_per_table = max_per_table
       @hierarchy = hierarchy
       @tables = []
+      @tables_arrangement_id = tables_arrangement_id
     end
 
     def random_distribution(people, random: Random.new)
@@ -50,7 +51,11 @@ module Tables
 
     def save!
       ActiveRecord::Base.transaction do
-        arrangement = TablesArrangement.create!
+        arrangement = TablesArrangement.find_or_create_by!(id: tables_arrangement_id)
+
+        self.tables_arrangement_id = arrangement.id
+
+        arrangement.seats.delete_all
 
         records_to_store = []
 

spec/services/tables/distribution_spec.rb

@@ -6,6 +6,39 @@ require 'rails_helper'
 
 module Tables
   RSpec.describe Distribution do
+    describe '#save!' do
+      
+      around do |example|
+        ActsAsTenant.with_tenant(create(:wedding)) do
+          example.run
+        end
+      end
+
+      let(:people) { create_list(:guest, 2, status: :invited) }
+      let(:distribution) do
+        described_class.new(min_per_table: 5, max_per_table: 10).tap{|d| d.random_distribution(people)}
+      end
+
+      context 'when tables_arrangement_id is nil' do
+
+
+        it { expect { distribution.save! }.to change { TablesArrangement.count }.by(1) }
+        it { expect { distribution.save! }.to change { Seat.count }.by(2) }
+      end
+
+      context 'when tables_arrangement_id is set' do
+        before do
+          existing_arrangement = TablesArrangement.create!
+
+          existing_arrangement.seats.create!(guest: people.first, table_number: 1)
+          distribution.tables_arrangement_id = existing_arrangement.id
+        end
+
+        it { expect { distribution.save! }.not_to change { TablesArrangement.count } }
+        it { expect { distribution.save! }.to change { Seat.count }.by(1) }
+      end
+    end
+
     describe '#random_distribution' do
       subject(:distribution) { described_class.new(min_per_table: 5, max_per_table: 10) }