Update and Recalculate Fees after Order Adjusted in Backend

- when update on adjustment in payment, recalculation of
  correct adjustment was not done
- the corresponding spec
- an id to easy the finding of the change of fees in the spec

app/models/spree/payment.rb

@@ -155,6 +155,7 @@ module Spree
       if adjustment
         adjustment.originator = payment_method
         adjustment.label = adjustment_label
+        adjustment.amount = payment_method.compute_amount(self)
         adjustment.save
       elsif !processing_refund? && payment_method.present?
         payment_method.create_adjustment(adjustment_label, self, true)

app/views/spree/admin/orders/_form/_adjustments.html.haml

@@ -6,7 +6,7 @@
         %tr
           %th= Spree.t('name')
           %th= Spree.t('amount')
-      %tbody.with-border
+      %tbody.with-border#order_adjustments
         - adjustments.each do |adjustment|
           %tr.total
             %td.strong= adjustment.label + ":"

spec/system/admin/order_spec.rb

@@ -172,6 +172,27 @@ RSpec.describe '
     expect(order.line_items.reload.map(&:product)).to include product
   end
 
+  context "When adding a product on an order with transaction fee" do
+    let(:order_with_fees) { create(:completed_order_with_fees, user:, distributor:, order_cycle: ) }
+
+    it 'recalculates transaction fee' do
+      login_as_admin
+      visit spree.edit_admin_order_path(order_with_fees)
+
+      transaction_fee = order_with_fees.all_adjustments.payment_fee.eligible.first.amount
+      expect(page.find("#order_adjustments").text).to have_content(transaction_fee)
+
+      select2_select product.name, from: 'add_variant_id', search: true
+      find('button.add_variant').click
+      sleep(1)
+
+      new_transaction_fee = order_with_fees.all_adjustments.payment_fee.eligible.first.amount
+
+      expect(new_transaction_fee).to be > transaction_fee
+      expect(page.find("#order_adjustments").text).to have_content(new_transaction_fee)
+    end
+  end
+
   shared_examples_for "Cancelling the order" do
     it "shows a modal about order cancellation" do
       expect(page).to have_content "This will cancel the current order."