Move tax charge logic out of checkout controller and update payment transition

app/controllers/split_checkout_controller.rb

@@ -24,7 +24,7 @@ class SplitCheckoutController < ::BaseController
   def edit
     redirect_to_step_based_on_order unless params[:step]
     check_step if params[:step]
-    recalculate_tax if params[:step] == "summary"
+    apply_voucher if @order.voucher_adjustments.present?
 
     flash_error_when_no_shipping_method_available if available_shipping_methods.none?
   end
@@ -309,12 +309,6 @@ class SplitCheckoutController < ::BaseController
     end
   end
 
-  def recalculate_tax
-    @order.create_tax_charge!
-    @order.update_order!
-
-    apply_voucher if @order.voucher_adjustments.present?
-  end
 
   def apply_voucher
     VoucherAdjustmentsService.calculate(@order)

app/models/spree/order/checkout.rb

@@ -77,7 +77,10 @@ module Spree
               before_transition to: :delivery, do: :ensure_available_shipping_rates
               before_transition to: :confirmation, do: :validate_payment_method!
 
-              after_transition to: :payment, do: :create_tax_charge!
+              after_transition to: :payment do |order|
+                order.create_tax_charge!
+                order.update_totals_and_states
+              end
               after_transition to: :complete, do: :finalize!
               after_transition to: :resumed,  do: :after_resume
               after_transition to: :canceled, do: :after_cancel

spec/controllers/spree/admin/orders_controller_spec.rb

@@ -57,7 +57,7 @@ describe Spree::Admin::OrdersController, type: :controller do
 
         it "updates fees and taxes and redirects to order details page" do
           expect(order).to receive(:recreate_all_fees!)
-          expect(order).to receive(:create_tax_charge!)
+          expect(order).to receive(:create_tax_charge!).at_least :once
 
           spree_put :update, params
 

spec/system/consumer/split_checkout_tax_not_incl_spec.rb

@@ -99,12 +99,12 @@ describe "As a consumer, I want to see adjustment breakdown" do
         choose "Delivery"
 
         click_button "Next - Payment method"
-        click_on "Next - Order summary"
-        click_on "Complete order"
 
         # DB checks
-        order_within_zone.reload
-        expect(order_within_zone.additional_tax_total).to eq(1.3)
+        expect(order_within_zone.reload.additional_tax_total).to eq(1.3)
+
+        click_on "Next - Order summary"
+        click_on "Complete order"
 
         # UI checks
         expect(page).to have_content("Confirmed")