CLDC-4212, CLDC-4213, CLDC-4214: Add 0.1% tolerance to all calculations that involve %s of a value (#3214)

* CLDC-4212: Add 0.1% tolerance to % calculations

this is to specifically allow 0.1% more or less than the calculation expects, for those that contain %s in them

this removes difficulties on adding 66.6% equity (or should it be 66.7%?)

* CLDC-4212: Remove discount soft validation

was replaced by a hard validation in CLDC-1899 so no longer serves a purpose

* CLDC-4212: Add tests

* fixup! CLDC-4212: Add 0.1% tolerance to % calculations

calculate a tolerance instead

* fixup! CLDC-4212: Add 0.1% tolerance to % calculations

update comment

app/models/sales_log.rb

@@ -268,6 +268,22 @@ class SalesLog < Log
     value * equity / 100
   end
 
+  def expected_shared_ownership_deposit_value_tolerance
+    return 1 unless value && equity
+
+    # we found that a fixed tolerance was not quite what we wanted here.
+    # CORE wants it so if a user say, has a 66.666% equity they can enter either 66.6% or 66.7% (or 66.5%)
+    # so in 2026 we base our tolerance off of a discount 0.1% higher or lower
+    if form.start_year_2026_or_later?
+      lower_bound = value * ((equity - 0.1) / 100)
+      upper_bound = value * ((equity + 0.1) / 100)
+
+      (upper_bound - lower_bound) / 2
+    else
+      1
+    end
+  end
+
   def stairbought_part_of_value
     return unless value && stairbought
 
@@ -468,6 +484,22 @@ class SalesLog < Log
     value - discount_amount
   end
 
+  def value_with_discount_tolerance
+    return 1 if value.blank? || discount.nil?
+
+    # we found that a simple tolerance was not quite what we wanted here.
+    # CORE wants it so if a user say, has a 66.6% discount then can enter either 66.6% or 66.7%
+    # so in 2026 we base our tolerance off of a discount 0.1% higher or lower
+    if form.start_year_2026_or_later?
+      discount_amount_lower_bound = value * (discount - 0.1) / 100
+      discount_amount_upper_bound = value * (discount + 0.1) / 100
+
+      (discount_amount_upper_bound - discount_amount_lower_bound) / 2
+    else
+      discount ? value * 0.05 / 100 : 1
+    end
+  end
+
   def mortgage_deposit_and_grant_total
     return if deposit.blank?
 

app/models/validations/sales/sale_information_validations.rb

@@ -80,10 +80,9 @@ module Validations::Sales::SaleInformationValidations
     return unless record.mortgage || record.mortgageused == 2 || record.mortgageused == 3
     return unless record.discount || record.grant || record.type == 29
 
-    # When a percentage discount is used, a percentage tolerance is needed to account for rounding errors
-    tolerance = record.discount ? record.value * 0.05 / 100 : 1
+    tolerance = record.value_with_discount_tolerance
 
-    if over_tolerance?(record.mortgage_deposit_and_grant_total, record.value_with_discount, tolerance, strict: !record.discount.nil?) && record.discounted_ownership_sale?
+    if over_tolerance?(record.mortgage_deposit_and_grant_total, record.value_with_discount, tolerance, strict: !record.discount.nil? || record.form.start_year_2026_or_later?) && record.discounted_ownership_sale?
       deposit_and_grant_sentence = record.grant.present? ? ", cash deposit (#{record.field_formatted_as_currency('deposit')}), and grant (#{record.field_formatted_as_currency('grant')})" : " and cash deposit (#{record.field_formatted_as_currency('deposit')})"
       discount_sentence = record.discount.present? ? " (#{record.field_formatted_as_currency('value')}) subtracted by the sum of the full purchase price (#{record.field_formatted_as_currency('value')}) multiplied by the percentage discount (#{record.discount}%)" : ""
       %i[mortgageused mortgage value deposit discount grant].each do |field|
@@ -204,10 +203,12 @@ module Validations::Sales::SaleInformationValidations
   def check_non_staircasing_socialhomebuy_mortgage(record)
     return unless record.cashdis
 
+    tolerance = record.expected_shared_ownership_deposit_value_tolerance
+
     if record.mortgage_used?
       return unless record.mortgage
 
-      if over_tolerance?(record.mortgage_deposit_and_discount_total, record.expected_shared_ownership_deposit_value, 1)
+      if over_tolerance?(record.mortgage_deposit_and_discount_total, record.expected_shared_ownership_deposit_value, tolerance, strict: record.form.start_year_2026_or_later?)
         %i[mortgage value deposit cashdis equity].each do |field|
           record.errors.add field, I18n.t("validations.sales.sale_information.#{field}.non_staircasing_mortgage.mortgage_used_socialhomebuy",
                                           mortgage: record.field_formatted_as_currency("mortgage"),
@@ -228,7 +229,7 @@ module Validations::Sales::SaleInformationValidations
                                                                  expected_shared_ownership_deposit_value: record.field_formatted_as_currency("expected_shared_ownership_deposit_value")).html_safe
       end
     elsif record.mortgage_not_used?
-      if over_tolerance?(record.deposit_and_discount_total, record.expected_shared_ownership_deposit_value, 1)
+      if over_tolerance?(record.deposit_and_discount_total, record.expected_shared_ownership_deposit_value, tolerance, strict: record.form.start_year_2026_or_later?)
         %i[mortgageused value deposit cashdis equity].each do |field|
           record.errors.add field, I18n.t("validations.sales.sale_information.#{field}.non_staircasing_mortgage.mortgage_not_used_socialhomebuy",
                                           deposit_and_discount_total: record.field_formatted_as_currency("deposit_and_discount_total"),
@@ -250,10 +251,12 @@ module Validations::Sales::SaleInformationValidations
   end
 
   def check_non_staircasing_non_socialhomebuy_mortgage(record)
+    tolerance = record.expected_shared_ownership_deposit_value_tolerance
+
     if record.mortgage_used?
       return unless record.mortgage
 
-      if over_tolerance?(record.mortgage_and_deposit_total, record.expected_shared_ownership_deposit_value, 1)
+      if over_tolerance?(record.mortgage_and_deposit_total, record.expected_shared_ownership_deposit_value, tolerance, strict: record.form.start_year_2026_or_later?)
         %i[mortgage value deposit equity].each do |field|
           record.errors.add field, I18n.t("validations.sales.sale_information.#{field}.non_staircasing_mortgage.mortgage_used",
                                           mortgage: record.field_formatted_as_currency("mortgage"),
@@ -272,7 +275,7 @@ module Validations::Sales::SaleInformationValidations
                                                                  expected_shared_ownership_deposit_value: record.field_formatted_as_currency("expected_shared_ownership_deposit_value")).html_safe
       end
     elsif record.mortgage_not_used?
-      if over_tolerance?(record.deposit, record.expected_shared_ownership_deposit_value, 1)
+      if over_tolerance?(record.deposit, record.expected_shared_ownership_deposit_value, tolerance, strict: record.form.start_year_2026_or_later?)
         %i[mortgageused value deposit equity].each do |field|
           record.errors.add field, I18n.t("validations.sales.sale_information.#{field}.non_staircasing_mortgage.mortgage_not_used",
                                           deposit: record.field_formatted_as_currency("deposit"),

app/models/validations/sales/soft_validations.rb

@@ -117,6 +117,7 @@ module Validations::Sales::SoftValidations
 
   def mortgage_plus_deposit_less_than_discounted_value?
     return unless mortgage && deposit && value && discount
+    return if form.start_year_2026_or_later?
 
     discounted_value = value * (100 - discount) / 100
     mortgage + deposit < discounted_value

spec/models/validations/sales/sale_information_validations_spec.rb

@@ -663,6 +663,46 @@ RSpec.describe Validations::Sales::SaleInformationValidations do
         expect(record.errors["grant"]).to be_empty
       end
     end
+
+    context "with year 2026", :aggregate_failures do
+      let(:saledate) { Time.zone.local(2026, 4, 1) }
+
+      context "when mortgage and deposit is exact" do
+        let(:record) { FactoryBot.build(:sales_log, saledate:, mortgage: 85_000, deposit: 5_000, value: 100_000, discount: 10, ownershipsch: 2, type: 9) }
+
+        it "does not add an error" do
+          sale_information_validator.validate_discounted_ownership_value(record)
+          expect(record.errors["mortgage"]).to be_empty
+          expect(record.errors["value"]).to be_empty
+          expect(record.errors["deposit"]).to be_empty
+          expect(record.errors["discount"]).to be_empty
+        end
+      end
+
+      context "when mortgage and deposit is within 0.1% discount tolerance" do
+        let(:record) { FactoryBot.build(:sales_log, saledate:, mortgage: 85_000, deposit: 5_000, value: 100_000, discount: 10.1, ownershipsch: 2, type: 9) }
+
+        it "does not add an error" do
+          sale_information_validator.validate_discounted_ownership_value(record)
+          expect(record.errors["mortgage"]).to be_empty
+          expect(record.errors["value"]).to be_empty
+          expect(record.errors["deposit"]).to be_empty
+          expect(record.errors["discount"]).to be_empty
+        end
+      end
+
+      context "when mortgage and deposit is outside 0.1% discount tolerance" do
+        let(:record) { FactoryBot.build(:sales_log, saledate:, mortgage: 85_000, deposit: 5_000, value: 100_000, discount: 10.2, ownershipsch: 2, type: 9) }
+
+        it "adds an error" do
+          sale_information_validator.validate_discounted_ownership_value(record)
+          expect(record.errors["mortgage"]).not_to be_empty
+          expect(record.errors["value"]).not_to be_empty
+          expect(record.errors["deposit"]).not_to be_empty
+          expect(record.errors["discount"]).not_to be_empty
+        end
+      end
+    end
   end
 
   describe "#validate_outright_sale_value_matches_mortgage_plus_deposit" do
@@ -1171,6 +1211,82 @@ RSpec.describe Validations::Sales::SaleInformationValidations do
         end
       end
     end
+
+    context "with year 2026", :aggregate_failures do
+      let(:saledate) { Time.zone.local(2026, 4, 1) }
+
+      context "when mortgage and deposit is exact" do
+        let(:record) { FactoryBot.build(:sales_log, mortgageused: 1, mortgage: 10_000, staircase: 2, deposit: 5_000, value: 100_000, equity: 15, ownershipsch: 1, type: 30, saledate:) }
+
+        it "does not add an error" do
+          sale_information_validator.validate_non_staircasing_mortgage(record)
+          expect(record.errors["mortgage"]).to be_empty
+          expect(record.errors["value"]).to be_empty
+          expect(record.errors["deposit"]).to be_empty
+          expect(record.errors["equity"]).to be_empty
+        end
+      end
+
+      context "when mortgage and deposit is within 0.1% equity tolerance" do
+        let(:record) { FactoryBot.build(:sales_log, mortgageused: 1, mortgage: 10_000, staircase: 2, deposit: 5_000, value: 100_000, equity: 15.1, ownershipsch: 1, type: 30, saledate:) }
+
+        it "does not add an error" do
+          sale_information_validator.validate_non_staircasing_mortgage(record)
+          expect(record.errors["mortgage"]).to be_empty
+          expect(record.errors["value"]).to be_empty
+          expect(record.errors["deposit"]).to be_empty
+          expect(record.errors["equity"]).to be_empty
+        end
+      end
+
+      context "when mortgage and deposit is outside 0.1% equity tolerance" do
+        let(:record) { FactoryBot.build(:sales_log, mortgageused: 1, mortgage: 10_000, staircase: 2, deposit: 5_000, value: 100_000, equity: 15.2, ownershipsch: 1, type: 30, saledate:) }
+
+        it "adds an error" do
+          sale_information_validator.validate_non_staircasing_mortgage(record)
+          expect(record.errors["mortgage"]).not_to be_empty
+          expect(record.errors["value"]).not_to be_empty
+          expect(record.errors["deposit"]).not_to be_empty
+          expect(record.errors["equity"]).not_to be_empty
+        end
+      end
+
+      context "when deposit (no mortgage) is exact" do
+        let(:record) { FactoryBot.build(:sales_log, mortgageused: 2, staircase: 2, deposit: 15_000, value: 100_000, equity: 15, ownershipsch: 1, type: 30, saledate:) }
+
+        it "does not add an error" do
+          sale_information_validator.validate_non_staircasing_mortgage(record)
+          expect(record.errors["mortgageused"]).to be_empty
+          expect(record.errors["value"]).to be_empty
+          expect(record.errors["deposit"]).to be_empty
+          expect(record.errors["equity"]).to be_empty
+        end
+      end
+
+      context "when deposit (no mortgage) is within 0.1% equity tolerance" do
+        let(:record) { FactoryBot.build(:sales_log, mortgageused: 2, staircase: 2, deposit: 15_000, value: 100_000, equity: 15.1, ownershipsch: 1, type: 30, saledate:) }
+
+        it "does not add an error" do
+          sale_information_validator.validate_non_staircasing_mortgage(record)
+          expect(record.errors["mortgageused"]).to be_empty
+          expect(record.errors["value"]).to be_empty
+          expect(record.errors["deposit"]).to be_empty
+          expect(record.errors["equity"]).to be_empty
+        end
+      end
+
+      context "when deposit (no mortgage) is outside 0.1% equity tolerance" do
+        let(:record) { FactoryBot.build(:sales_log, mortgageused: 2, staircase: 2, deposit: 15_000, value: 100_000, equity: 15.2, ownershipsch: 1, type: 30, saledate:) }
+
+        it "adds an error" do
+          sale_information_validator.validate_non_staircasing_mortgage(record)
+          expect(record.errors["mortgageused"]).not_to be_empty
+          expect(record.errors["value"]).not_to be_empty
+          expect(record.errors["deposit"]).not_to be_empty
+          expect(record.errors["equity"]).not_to be_empty
+        end
+      end
+    end
   end
 
   describe "#validate_staircasing_mortgage" do