Admin can modify a taxed adjustment on an order

app/controllers/spree/admin/adjustments_controller_decorator.rb

@@ -2,9 +2,17 @@ module Spree
   module Admin
     AdjustmentsController.class_eval do
       before_filter :set_included_tax, only: :create
+      before_filter :set_default_tax_rate, only: :edit
 
       private
 
+      def set_default_tax_rate
+        if @adjustment.included_tax > 0 && TaxRate.count == 1
+          @tax_rate_id = TaxRate.first.id
+        end
+      end
+
+
       def set_included_tax
         if params[:tax_rate_id].present?
           tax_rate = TaxRate.find params[:tax_rate_id]

app/views/spree/admin/adjustments/_edit_form.html.haml

@@ -0,0 +1,25 @@
+.row
+  .alpha.three.columns
+    = f.field_container :amount do
+      = f.label :amount, raw(t(:amount) + content_tag(:span, " *", :class => "required"))
+      = text_field :adjustment, :amount, :class => 'fullwidth'
+      = f.error_message_on :amount
+
+  .three.columns
+    = f.field_container :included_tax do
+      = f.label :included_tax, t(:included_tax)
+      = text_field :adjustment, :included_tax, disabled: true, class: 'fullwidth'
+      = f.error_message_on :included_tax
+
+  .omega.three.columns
+    = f.field_container :tax_rate_id do
+      = f.label :tax_rate_id, t(:tax)
+      = select_tag :tax_rate_id, options_from_collection_for_select(Spree::TaxRate.all, :id, :name, @tax_rate_id), prompt: t(:remove_tax), class: 'select2 fullwidth'
+      = f.error_message_on :tax_rate_id
+
+.row
+  .alpha.omega.twelve.columns
+    = f.field_container :label do
+      = f.label :label, raw(t(:description) + content_tag(:span, " *", :class => "required"))
+      = text_field :adjustment, :label, :class => 'fullwidth'
+      = f.error_message_on :label

config/locales/en.yml

@@ -38,4 +38,5 @@ en:
   footer_about_url: "About URL"
   footer_tos_url: "Terms of Service URL"
   invoice: "Invoice"
-  included_tax: "Included tax"
+  included_tax: "Included tax"
+  remove_tax: "Remove tax"

spec/features/admin/orders_spec.rb

@@ -129,6 +129,39 @@ feature %q{
     page.should have_selector 'td.included-tax', text: '10'
   end
 
+  scenario "modifying taxed adjustments on an order" do
+    # Given a tax rate and a taxed adjustment
+    tax_rate = create(:tax_rate, name: 'GST', calculator: build(:calculator, preferred_amount: 10))
+    adjustment = create(:adjustment, adjustable: @order, amount: 110, included_tax: 10)
+
+    # When I go to the adjustments page for the order
+    login_to_admin_section
+    visit spree.admin_orders_path
+    page.find('td.actions a.icon-edit').click
+    click_link 'Adjustments'
+    page.find('td.actions a.icon-edit').click
+
+    # Then I should see the uneditable included tax and our tax rate as the default
+    page.should have_field :adjustment_included_tax, with: '10.00', disabled: true
+    page.should have_select :tax_rate_id, selected: 'GST'
+
+    # When I edit the adjustment, removing the tax
+    select 'Remove tax', from: :tax_rate_id
+    click_button 'Continue'
+
+    # Then the adjustment tax should be cleared
+    page.should have_selector 'td.amount', text: '110'
+    page.should have_selector 'td.included-tax', text: '0'
+  end
+
+  scenario "modifying an untaxed adjustment on an order" do
+    # Given a tax rate and an untaxed adjustment
+    # When I go to the adjustments page for the order
+    # Then I should see 'Remove tax' as the default tax rate
+    # When I edit the adjustment, setting a tax rate
+    # Then the adjustment tax should be recalculated
+  end
+
 
   context "as an enterprise manager" do
     let(:coordinator1) { create(:distributor_enterprise) }