test: add new test

app/models/validations/household_validations.rb

@@ -202,6 +202,10 @@ private
     economic_status == 10
   end
 
+  def tenant_is_partner?(relationship)
+    relationship == "P"
+  end
+
   def tenant_is_child?(relationship)
     relationship == "C"
   end

app/models/validations/sales/household_validations.rb

@@ -13,4 +13,10 @@ module Validations::Sales::HouseholdValidations
       record.errors.add :base, I18n.t("validations.household.relat.one_partner")
     end
   end
+
+private
+
+  def tenant_is_partner?(relationship)
+    relationship == "P"
+  end
 end

app/models/validations/shared_validations.rb

@@ -68,8 +68,4 @@ module Validations::SharedValidations
 
     { scope: status, date: date&.to_formatted_s(:govuk_date), deactivation_date: closest_reactivation&.deactivation_date&.to_formatted_s(:govuk_date) }
   end
-
-  def tenant_is_partner?(relationship)
-    relationship == "P"
-  end
 end

spec/models/validations/sales/household_validations_spec.rb

@@ -46,4 +46,36 @@ RSpec.describe Validations::Sales::HouseholdValidations do
       end
     end
   end
+
+  describe "#validate_partner_count" do
+    context "when one partner" do
+      let(:record) { FactoryBot.build(:sales_log, relat2: "P", relat3: nil, relat4: nil, relat5: nil, relat6: nil) }
+
+      it "does not add an error" do
+        household_validator.validate_partner_count(record)
+
+        expect(record.errors).not_to be_present
+      end
+    end
+
+    context "when blank" do
+      let(:record) { FactoryBot.build(:sales_log, relat2: nil, relat3: nil, relat4: nil, relat5: nil, relat6: nil) }
+
+      it "does not add an error" do
+        household_validator.validate_partner_count(record)
+
+        expect(record.errors).not_to be_present
+      end
+    end
+
+    context "when two partners" do
+      let(:record) { FactoryBot.build(:sales_log, relat2: "P", relat3: "P", relat4: nil, relat5: nil, relat6: nil) }
+
+      it "adds an error" do
+        household_validator.validate_partner_count(record)
+
+        expect(record.errors).to be_present
+      end
+    end
+  end
 end