Add derived variables to sales log

app/models/derived_variables/sales_log_variables.rb

@@ -0,0 +1,5 @@
+module DerivedVariables::SalesLogVariables
+  def set_derived_fields!
+    self.ethnic = 17 if ethnic_refused?
+  end
+end

app/models/lettings_log.rb

@@ -372,10 +372,6 @@ class LettingsLog < Log
     hb == 7
   end
 
-  def ethnic_refused?
-    ethnic_group == 17
-  end
-
   def receives_housing_related_benefits?
     if collection_start_year <= 2021
       receives_housing_benefit_only? || receives_uc_with_housing_element_excl_housing_benefit? ||

app/models/log.rb

@@ -36,6 +36,10 @@ class Log < ApplicationRecord
     false
   end
 
+  def ethnic_refused?
+    ethnic_group == 17
+  end
+
 private
 
   def update_status!

app/models/sales_log.rb

@@ -3,10 +3,15 @@ class SalesLogValidator < ActiveModel::Validator
 end
 
 class SalesLog < Log
+  include DerivedVariables::SalesLogVariables
+
   self.inheritance_column = :_type_disabled
+
   has_paper_trail
 
   validates_with SalesLogValidator
+  before_validation :set_derived_fields!
+  before_validation :reset_invalidated_dependent_fields!
 
   scope :filter_by_year, ->(year) { where(saledate: Time.zone.local(year.to_i, 4, 1)...Time.zone.local(year.to_i + 1, 4, 1)) }
   scope :search_by, ->(param) { filter_by_id(param) }

spec/models/lettings_log_spec.rb

@@ -1,4 +1,5 @@
 require "rails_helper"
+require "shared/shared_examples_for_derived_fields"
 
 RSpec.describe LettingsLog do
   let(:owning_organisation) { FactoryBot.create(:organisation) }
@@ -10,6 +11,8 @@ RSpec.describe LettingsLog do
     allow(FormHandler.instance).to receive(:current_lettings_form).and_return(fake_2021_2022_form)
   end
 
+  include_examples "shared examples for derived fields", :lettings_log
+
   it "inherits from log" do
     expect(described_class).to be < Log
     expect(described_class).to be < ApplicationRecord

spec/models/sales_log_spec.rb

@@ -1,9 +1,12 @@
 require "rails_helper"
+require "shared/shared_examples_for_derived_fields"
 
 RSpec.describe SalesLog, type: :model do
   let(:owning_organisation) { FactoryBot.create(:organisation) }
   let(:created_by_user) { FactoryBot.create(:user) }
 
+  include_examples "shared examples for derived fields", :sales_log
+
   it "inherits from log" do
     expect(described_class).to be < Log
     expect(described_class).to be < ApplicationRecord

spec/shared/shared_examples_for_derived_fields.rb

@@ -0,0 +1,17 @@
+require "rails_helper"
+
+RSpec.shared_examples "shared examples for derived fields" do |log_type|
+  describe "sets ethnic based on the value of ethnic_refused" do
+    it "is set to 17 when ethnic_group is 17" do
+      log = FactoryBot.build(log_type, ethnic_group: 17, ethnic: nil)
+
+      expect { log.set_derived_fields! }.to change(log, :ethnic).from(nil).to(17)
+    end
+
+    it "is is not modified otherwise" do
+      log = FactoryBot.build(log_type, ethnic_group: nil, ethnic: nil)
+
+      expect { log.set_derived_fields! }.not_to change(log, :ethnic)
+    end
+  end
+end