app/services/affinity_groups_hierarchy.rb

@@ -14,23 +14,23 @@ class AffinityGroupsHierarchy < Array
     end
   end
 
-  def find(name)
-    @references[name]
+  def find(id)
+    @references[id]
   end
 
-  def <<(name)
-    new_node = Tree::TreeNode.new(name)
-    super(new_node).tap { @references[name] = new_node }
+  def <<(id)
+    new_node = Tree::TreeNode.new(id)
+    super(new_node).tap { @references[id] = new_node }
   end
 
-  def register_child(parent_name, child_name)
-    @references[parent_name] << Tree::TreeNode.new(child_name).tap { |child_node| @references[child_name] = child_node }
+  def register_child(parent_id, child_id)
+    @references[parent_id] << Tree::TreeNode.new(child_id).tap { |child_node| @references[child_id] = child_node }
   end
 
-  def distance(name_a, name_b)
-    return nil if @references[name_a].nil? || @references[name_b].nil?
+  def distance(id_a, id_b)
+    return nil if @references[id_a].nil? || @references[id_b].nil?
 
-    @references[name_a].distance_to_common_ancestor(@references[name_b])
+    @references[id_a].distance_to_common_ancestor(@references[id_b])
   end
 
   private

app/services/tables/discomfort_calculator.rb

@@ -14,7 +14,7 @@ module Tables
     private
 
     def cohesion_penalty
-      table.map { |guest| guest.affinity_group_list.first }.tally.to_a.combination(2).sum do |(a, count_a), (b, count_b)|
+      table.map(&:group_id).tally.to_a.combination(2).sum do |(a, count_a), (b, count_b)|
         distance = AffinityGroupsHierarchy.instance.distance(a, b)
 
         next count_a * count_b if distance.nil?

spec/services/tables/discomfort_calculator_spec.rb

@@ -5,6 +5,11 @@ module Tables
   RSpec.describe DiscomfortCalculator do
     let(:calculator) { described_class.new(table) }
 
+    let(:family) { create(:group, name: 'family') }
+    let(:friends) { create(:group, name: 'friends') }
+    let(:work) { create(:group, name: 'work') }
+    let(:school) { create(:group, name: 'school') }
+
     describe '#cohesion_penalty' do
       before do
         # Overridden in each test except trivial cases
@@ -14,16 +19,16 @@ module Tables
           allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(group, group).and_return(0)
         end
 
-        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with('family', 'friends').and_return(nil)
-        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with('friends', 'work').and_return(1)
-        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with('family', 'work').and_return(2)
-        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with('family', 'school').and_return(3)
-        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with('friends', 'school').and_return(4)
-        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with('work', 'school').and_return(5)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(family.id, friends.id).and_return(nil)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(friends.id, work.id).and_return(1)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(family.id, work.id).and_return(2)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(family.id, school.id).and_return(3)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(friends.id, school.id).and_return(4)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(work.id, school.id).and_return(5)
       end
       context 'when the table contains just two guests' do
         context 'when they belong to the same group' do
-          let(:table) { create_list(:guest, 2, affinity_group_list: ['family']) }
+          let(:table) { create_list(:guest, 2, group: family) }
 
           it { expect(calculator.send(:cohesion_penalty)).to eq(0) }
         end
@@ -31,8 +36,8 @@ module Tables
         context 'when they belong to completely unrelated groups' do
           let(:table) do
             [
-              create(:guest, affinity_group_list: ['family']),
-              create(:guest, affinity_group_list: ['friends'])
+              create(:guest, group: family),
+              create(:guest, group: friends)
             ]
           end
           it { expect(calculator.send(:cohesion_penalty)).to eq(1) }
@@ -41,8 +46,8 @@ module Tables
         context 'when they belong to groups at a distance of 1' do
           let(:table) do
             [
-              create(:guest, affinity_group_list: ['friends']),
-              create(:guest, affinity_group_list: ['work'])
+              create(:guest, group: friends),
+              create(:guest, group: work)
             ]
           end
 
@@ -52,8 +57,8 @@ module Tables
         context 'when they belong to groups at a distance of 2' do
           let(:table) do
             [
-              create(:guest, affinity_group_list: ['family']),
-              create(:guest, affinity_group_list: ['work'])
+              create(:guest, group: family),
+              create(:guest, group: work)
             ]
           end
 
@@ -63,8 +68,8 @@ module Tables
         context 'when they belong to groups at a distance of 3' do
           let(:table) do
             [
-              create(:guest, affinity_group_list: ['family']),
-              create(:guest, affinity_group_list: ['school'])
+              create(:guest, group: family),
+              create(:guest, group: school)
             ]
           end
 
@@ -75,9 +80,9 @@ module Tables
       context 'when the table contains three guests' do
         let(:table) do
           [
-            create(:guest, affinity_group_list: ['family']),
-            create(:guest, affinity_group_list: ['friends']),
-            create(:guest, affinity_group_list: ['work'])
+            create(:guest, group: family),
+            create(:guest, group: friends),
+            create(:guest, group: work)
           ]
         end
 
@@ -89,10 +94,10 @@ module Tables
       context 'when the table contains four guests of different groups' do
         let(:table) do
           [
-            create(:guest, affinity_group_list: ['family']),
-            create(:guest, affinity_group_list: ['friends']),
-            create(:guest, affinity_group_list: ['work']),
-            create(:guest, affinity_group_list: ['school'])
+            create(:guest, group: family),
+            create(:guest, group: friends),
+            create(:guest, group: work),
+            create(:guest, group: school)
           ]
         end
 
@@ -105,8 +110,8 @@ module Tables
       context 'when the table contains four guests of two evenly split groups' do
         let(:table) do
           [
-            create_list(:guest, 2, affinity_group_list: ['family']),
-            create_list(:guest, 2, affinity_group_list: ['friends'])
+            create_list(:guest, 2, group: family),
+            create_list(:guest, 2, group: friends)
           ].flatten
         end
 
@@ -118,8 +123,8 @@ module Tables
       context 'when the table contains six guests of two unevenly split groups' do
         let(:table) do
           [
-            create_list(:guest, 2, affinity_group_list: ['family']),
-            create_list(:guest, 4, affinity_group_list: ['friends'])
+            create_list(:guest, 2, group: family),
+            create_list(:guest, 4, group: friends)
           ].flatten
         end
 
@@ -131,9 +136,9 @@ module Tables
       context 'when the table contains six guests of three evenly split groups' do
         let(:table) do
           [
-            create_list(:guest, 2, affinity_group_list: ['family']),
-            create_list(:guest, 2, affinity_group_list: ['friends']),
-            create_list(:guest, 2, affinity_group_list: ['work'])
+            create_list(:guest, 2, group: family),
+            create_list(:guest, 2, group: friends),
+            create_list(:guest, 2, group: work)
           ].flatten
         end
 
@@ -145,9 +150,9 @@ module Tables
       context 'when the table contains six guests of three unevenly split groups' do
         let(:table) do
           [
-            create_list(:guest, 3, affinity_group_list: ['family']),
-            create_list(:guest, 2, affinity_group_list: ['friends']),
-            create_list(:guest, 1, affinity_group_list: ['work'])
+            create_list(:guest, 3, group: family),
+            create_list(:guest, 2, group: friends),
+            create_list(:guest, 1, group: work)
           ].flatten
         end