CLDC-1905 infer vacancy reason when renewal (#1321)

* add test for derivation of relet when renewal

* derive rsnvac when renewal set to yes, reset rsnvac when renewal set to no

* add test to ensure vacancy reasion is reset if letting is not a renewal

app/models/derived_variables/lettings_log_variables.rb

@@ -48,6 +48,7 @@ module DerivedVariables::LettingsLogVariables
       self.offered = 0
       self.voiddate = startdate
       self.first_time_property_let_as_social_housing = 0
+      self.rsnvac = 14
       if is_general_needs?
         # fixed term
         self.prevten = 32 if managing_organisation&.provider_type == "PRP"

app/models/lettings_log.rb

@@ -518,6 +518,7 @@ private
   def reset_derived_questions
     dependent_questions = { waityear: [{ key: :renewal, value: 0 }],
                             referral: [{ key: :renewal, value: 0 }],
+                            rsnvac: [{ key: :renewal, value: 0 }],
                             underoccupation_benefitcap: [{ key: :renewal, value: 0 }],
                             wchair: [{ key: :needstype, value: 1 }],
                             location_id: [{ key: :needstype, value: 1 }] }

spec/models/lettings_log_spec.rb

@@ -1468,6 +1468,12 @@ RSpec.describe LettingsLog do
         expect(record_from_db["first_time_property_let_as_social_housing"]).to eq(0)
         expect(lettings_log["first_time_property_let_as_social_housing"]).to eq(0)
       end
+
+      it "derives vacancy reason as relet" do
+        record_from_db = ActiveRecord::Base.connection.execute("select rsnvac from lettings_logs where id=#{lettings_log.id}").to_a[0]
+        expect(record_from_db["rsnvac"]).to eq(14)
+        expect(lettings_log["rsnvac"]).to eq(14)
+      end
     end
 
     context "when answering the household characteristics questions" do
@@ -1992,6 +1998,21 @@ RSpec.describe LettingsLog do
         expect(record_from_db["waityear"]).to eq(nil)
         expect(lettings_log["waityear"]).to eq(nil)
       end
+
+      it "resets inferred vacancy reason value" do
+        vacancy_reason = "rsnvac"
+
+        lettings_log.update!({ renewal: 1 })
+
+        record_from_db = ActiveRecord::Base.connection.execute("select #{vacancy_reason} from lettings_logs where id=#{lettings_log.id}").to_a[0]
+        expect(record_from_db[vacancy_reason]).to eq(14)
+        expect(lettings_log[vacancy_reason]).to eq(14)
+
+        lettings_log.update!({ renewal: 0 })
+        record_from_db = ActiveRecord::Base.connection.execute("select #{vacancy_reason} from lettings_logs where id=#{lettings_log.id}").to_a[0]
+        expect(record_from_db[vacancy_reason]).to eq(nil)
+        expect(lettings_log[vacancy_reason]).to eq(nil)
+      end
     end
 
     context "when it changes from a supported housing to not a supported housing" do