write tests that invalid answers are cleared when the start date of a log is changed

spec/factories/lettings_log.rb

@@ -158,6 +158,9 @@ FactoryBot.define do
       sheltered { 0 }
       household_charge { 0 }
     end
+    trait :sheltered_housing do
+      needstype { 2 }
+    end
     created_at { Time.zone.today }
     updated_at { Time.zone.today }
   end

spec/factories/sales_log.rb

@@ -10,6 +10,9 @@ FactoryBot.define do
       type { 8 }
       saledate { Time.utc(2023, 2, 2, 10, 36, 49) }
     end
+    trait :shared_ownership do
+      ownershipsch { 1 }
+    end
     trait :completed do
       ownershipsch { 2 }
       type { 8 }

spec/models/lettings_log_spec.rb

@@ -2620,6 +2620,40 @@ RSpec.describe LettingsLog do
         end
       end
     end
+
+    context "when the collection year is changed" do
+      around do |example|
+        Timecop.freeze(now) do
+          Singleton.__init__(FormHandler)
+          FormHandler.instance.use_real_forms!
+          example.run
+        end
+        Timecop.return
+      end
+
+      let(:lettings_log) { FactoryBot.create(:lettings_log, :about_completed, :sheltered_housing, startdate: now, sheltered:) }
+      let(:now) { Time.zone.local(2023, 6, 1) }
+
+      context "and selected answer options are no longer valid" do
+        let(:sheltered) { 5 }
+
+        it "clears those values" do
+          expect(lettings_log.sheltered).to be 5
+          lettings_log.update!(startdate: Time.zone.local(2023, 1, 1))
+          expect(lettings_log.sheltered).to be nil
+        end
+      end
+
+      context "and selected answer options are still valid" do
+        let(:sheltered) { 2 }
+
+        it "does not clear those values" do
+          expect(lettings_log.sheltered).to be 2
+          lettings_log.update!(startdate: Time.zone.local(2023, 1, 1))
+          expect(lettings_log.sheltered).to be 2
+        end
+      end
+    end
   end
 
   describe "tshortfall_unknown?" do

spec/models/sales_log_spec.rb

@@ -222,6 +222,42 @@ RSpec.describe SalesLog, type: :model do
     end
   end
 
+  describe "resetting invalidated fields" do
+    context "when the collection year is changed" do
+      around do |example|
+        Timecop.freeze(now) do
+          Singleton.__init__(FormHandler)
+          FormHandler.instance.use_real_forms!
+          example.run
+        end
+        Timecop.return
+      end
+
+      let(:sales_log) { FactoryBot.create(:sales_log, :shared_ownership, saledate: now, type:) }
+      let(:now) { Time.zone.local(2023, 6, 1) }
+
+      context "and selected answer options are no longer valid" do
+        let(:type) { 32 }
+
+        it "clears those values" do
+          expect(sales_log.type).to be 32
+          sales_log.update!(saledate: Time.zone.local(2023, 1, 1))
+          expect(sales_log.type).to be nil
+        end
+      end
+
+      context "and selected answer options are still valid" do
+        let(:type) { 24 }
+
+        it "does not clear those values" do
+          expect(sales_log.type).to be 24
+          sales_log.update!(saledate: Time.zone.local(2023, 1, 1))
+          expect(sales_log.type).to be 24
+        end
+      end
+    end
+  end
+
   context "when saving addresses" do
     before do
       stub_request(:get, /api.postcodes.io/)