Move taxing of enterprise fees to TaxRate

app/models/spree/adjustment.rb

@@ -35,10 +35,12 @@ module Spree
     # So we don't need the option `dependent: :destroy` as long as
     # AdjustmentMetadata has no destroy logic itself.
     has_one :metadata, class_name: 'AdjustmentMetadata'
+    has_many :adjustments, as: :adjustable, dependent: :destroy
 
     belongs_to :adjustable, polymorphic: true
     belongs_to :originator, -> { with_deleted }, polymorphic: true
     belongs_to :order, class_name: "Spree::Order"
+    belongs_to :tax_category, class_name: 'Spree::TaxCategory'
 
     belongs_to :tax_rate, -> { where spree_adjustments: { originator_type: 'Spree::TaxRate' } },
                foreign_key: 'originator_id'

app/models/spree/order.rb

@@ -295,6 +295,7 @@ module Spree
     def create_tax_charge!
       Spree::TaxRate.adjust(self, line_items)
       Spree::TaxRate.adjust(self, shipments) if shipments.any?
+      Spree::TaxRate.adjust(self, all_adjustments.enterprise_fee)
     end
 
     def name

lib/open_food_network/enterprise_fee_applicator.rb

@@ -11,11 +11,11 @@ module OpenFoodNetwork
     private
 
     def create_adjustment(label, adjustable)
-      adjustment = enterprise_fee.create_adjustment(label, adjustable, true)
+      adjustment = enterprise_fee.create_adjustment(
+        label, adjustable, true, "closed", tax_category(adjustable)
+      )
 
       AdjustmentMetadata.create! adjustment: adjustment, enterprise: enterprise_fee.enterprise, fee_name: enterprise_fee.name, fee_type: enterprise_fee.fee_type, enterprise_role: role
-
-      adjustment.set_absolute_included_tax! adjustment_tax(adjustment)
     end
 
     def line_item_adjustment_label
@@ -30,11 +30,11 @@ module OpenFoodNetwork
       I18n.t(:enterprise_fee_by, type: enterprise_fee.fee_type, role: role, enterprise_name: enterprise_fee.enterprise.name)
     end
 
-    def adjustment_tax(adjustment)
-      tax_rates = TaxRateFinder.tax_rates_of(adjustment)
-
-      tax_rates.select(&:included_in_price).sum do |rate|
-        rate.compute_tax adjustment.amount
+    def tax_category(target)
+      if target.is_a?(Spree::LineItem) && enterprise_fee.inherits_tax_category?
+        target.product.tax_category
+      else
+        enterprise_fee.tax_category
       end
     end
   end

lib/spree/core/calculated_adjustments.rb

@@ -26,7 +26,7 @@ module Spree
           #   (which is any class that has_many :adjustments) and sets amount based on the
           #   calculator as applied to the given calculable (Order, LineItems[], Shipment, etc.)
           # By default the adjustment will not be considered mandatory
-          def create_adjustment(label, adjustable, mandatory = false, state = "closed")
+          def create_adjustment(label, adjustable, mandatory = false, state = "closed", tax_category = nil)
             amount = compute_amount(adjustable)
             return if amount.zero? && !mandatory
 
@@ -36,7 +36,8 @@ module Spree
               order: order_object_for(adjustable),
               label: label,
               mandatory: mandatory,
-              state: state
+              state: state,
+              tax_category: tax_category
             }
 
             if adjustable.respond_to?(:adjustments)

spec/models/spree/order/state_machine_spec.rb

@@ -55,7 +55,7 @@ describe Spree::Order do
       end
 
       it "adjusts tax rates when transitioning to payment" do
-        expect(Spree::TaxRate).to receive(:adjust)
+        expect(Spree::TaxRate).to receive(:adjust).at_least(:once)
         order.next!
       end
     end