404 when no invoice found

it's mostly a problem for crawlers
at the app level it feels like there should be some better encapsulation of this crosscutting concern of not existing data

for now, treating each resource separately, but tests together

rails_application/app/controllers/application_controller.rb

@@ -6,4 +6,8 @@ def event_store
   def command_bus
     Rails.configuration.command_bus
   end
+
+  def not_found
+    render file: "#{Rails.root}/public/404.html", layout: false, status: :not_found
+  end
 end

rails_application/app/controllers/invoices_controller.rb

@@ -1,6 +1,7 @@
 class InvoicesController < ApplicationController
   def show
     @invoice = Invoices::Invoice.find_by_order_uid(params[:id])
+    not_found unless @invoice
   end
 
   def create

rails_application/app/controllers/orders_controller.rb

@@ -132,7 +132,4 @@ def capture_payment_cmd(order_id)
     Payments::CapturePayment.new(order_id: order_id)
   end
 
-  def not_found
-    render file: "#{Rails.root}/public/404.html", layout: false, status: :not_found
-  end
 end

rails_application/test/integration/orders_test.rb

@@ -91,11 +91,6 @@ def test_expiring_orders
     assert_select("td", "Expired")
   end
 
-  def test_order_not_found
-    get "/orders/123"
-    assert_response :not_found
-  end
-
   def test_cancel
     shopify_id = register_customer("Shopify")
 

rails_application/test/integration/routing_404_test.rb

@@ -0,0 +1,15 @@
+require "test_helper"
+
+class MissingResourcesTest < InMemoryRESIntegrationTestCase
+
+
+  def test_order_not_found
+    get "/orders/123"
+    assert_response :not_found
+  end
+
+  def test_invoice_not_found
+    get "/invoices/123"
+    assert_response :not_found
+  end
+end