Add basic tests for the local_discomfort formula

Gemfile

@@ -50,6 +50,7 @@ group :development, :test do
   gem 'rspec-rails', '~> 6.1.0'
   gem 'faker'
   gem 'pry'
+  gem "factory_bot_rails"
 end
 
 group :development do

Gemfile.lock

@@ -100,6 +100,11 @@ GEM
     diff-lcs (1.5.0)
     drb (2.2.1)
     erubi (1.13.0)
+    factory_bot (6.4.6)
+      activesupport (>= 5.0.0)
+    factory_bot_rails (6.4.3)
+      factory_bot (~> 6.4)
+      railties (>= 5.0.0)
     faker (3.1.1)
       i18n (>= 1.8.11, < 2)
     globalid (1.2.1)
@@ -268,6 +273,7 @@ DEPENDENCIES
   acts-as-taggable-on
   bootsnap
   debug
+  factory_bot_rails
   faker
   importmap-rails
   jbuilder

spec/factories/guest.rb

@@ -0,0 +1,8 @@
+FactoryBot.define do
+  factory :guest do
+    first_name { Faker::Name.first_name }
+    last_name { Faker::Name.last_name }
+    email { Faker::Internet.email }
+    phone { Faker::PhoneNumber.cell_phone }
+  end
+end

spec/rails_helper.rb

@@ -62,4 +62,5 @@ RSpec.configure do |config|
   config.filter_rails_from_backtrace!
   # arbitrary gems may also be filtered via:
   # config.filter_gems_from_backtrace("gem name")
+  config.include FactoryBot::Syntax::Methods
 end

spec/services/tables/distribution_spec.rb

@@ -0,0 +1,45 @@
+require 'rails_helper'
+
+module Tables
+  RSpec.describe Distribution do
+    describe '#local_discomfort' do
+      let(:service) { described_class.new(min_per_table: 5, max_per_table: 5) }
+      before { service.tables = [table] }
+
+      context 'when there is just one group in the table' do
+        let(:table) do
+          create_list(:guest, 3).each do |guest|
+            guest.affinity_group_list.add('family')
+            guest.save!
+          end
+        end
+
+        it { expect(service.send(:local_discomfort, table)).to eq(0) }
+      end
+
+      context 'when the table contains two groups' do
+        let(:table) do
+          guests = create_list(:guest, 3)
+          guests[0].affinity_group_list.add('family')
+          guests[1].affinity_group_list.add('friends')
+          guests[2].affinity_group_list.add('family')
+          guests.each(&:save!)
+        end
+
+        it { expect(service.send(:local_discomfort, table)).to eq(10) }
+      end
+
+      context 'when the table contains three groups' do
+        let(:table) do
+          guests = create_list(:guest, 3)
+          guests[0].affinity_group_list.add('family')
+          guests[1].affinity_group_list.add('friends')
+          guests[2].affinity_group_list.add('work')
+          guests.each(&:save!)
+        end
+
+        it { expect(service.send(:local_discomfort, table)).to eq(20) }
+      end
+    end
+  end
+end