Introduce TaxCategories to ShippingMethods

app/controllers/spree/admin/shipping_methods_controller.rb

@@ -79,6 +79,7 @@ module Spree
 
       def load_data
         @available_zones = Zone.order(:name)
+        @tax_categories = Spree::TaxCategory.order(:name)
         @calculators = ShippingMethod.calculators.sort_by(&:name)
       end
 

app/models/calculator/default_tax.rb

@@ -13,6 +13,8 @@ module Calculator
       case computable
       when Spree::Order
         compute_order(computable)
+      when Spree::Shipment
+        compute_shipment(computable)
       when Spree::LineItem
         compute_line_item(computable)
       end
@@ -70,17 +72,19 @@ module Calculator
         .sum { |applicator| applicator.enterprise_fee.compute_amount(order) }
     end
 
-    def compute_line_item(line_item)
-      if line_item.tax_category == rate.tax_category
+    def compute_shipment_or_line_item(item)
+      if item.tax_category == rate.tax_category
         if rate.included_in_price
-          deduced_total_by_rate(line_item.total, rate)
+          deduced_total_by_rate(item.amount, rate)
         else
-          round_to_two_places(line_item.total * rate.amount)
+          round_to_two_places(item.amount * rate.amount)
         end
       else
         0
       end
     end
+    alias_method :compute_shipment, :compute_shipment_or_line_item
+    alias_method :compute_line_item, :compute_shipment_or_line_item
 
     def round_to_two_places(amount)
       BigDecimal(amount.to_s).round(2, BigDecimal::ROUND_HALF_UP)

app/models/spree/shipment.rb

@@ -104,6 +104,10 @@ module Spree
       save!
     end
 
+    def tax_category
+      selected_shipping_rate.try(:shipping_method).try(:tax_category)
+    end
+
     def refresh_rates
       return shipping_rates if shipped?
 

app/models/spree/shipping_method.rb

@@ -23,6 +23,8 @@ module Spree
                                     class_name: 'Spree::Zone',
                                     foreign_key: 'shipping_method_id'
 
+    belongs_to :tax_category, class_name: 'Spree::TaxCategory'
+
     validates :name, presence: true
     validate :distributor_validation
     validate :at_least_one_shipping_category

app/views/spree/admin/shipping_methods/_form.html.haml

@@ -43,9 +43,14 @@
       = f.hidden_field :tag_list, "ng-value" => "shippingMethod.tag_list"
       %tags-with-translation#something{ object: "shippingMethod", 'find-tags' => 'findTags(query)' }
 
-  
+
   = render partial: 'spree/admin/shared/calculator_fields', locals: { f: f }
 
+  %fieldset.tax_categories.no-border-bottom
+    = f.field_container :tax_categories do
+      = f.select :tax_category_id, @tax_categories.map { |tc| [tc.name, tc.id] }, {}, :class => "select2 fullwidth"
+      = error_message_on :shipping_method, :tax_category_id
+
   %fieldset.categories.no-border-bottom
     %legend{align: "center"}= t('.categories')
     = f.field_container :categories do
@@ -56,7 +61,7 @@
           %br/
       = error_message_on :shipping_method, :shipping_category_id
 
-  
+
   %fieldset.no-border-bottom
     %legend{align: "center"}= t('.zones')
     = f.field_container :zones do