Final test

test/integration/product_attributes_test.rb

@@ -0,0 +1,20 @@
+require 'test_helper'
+
+class ProductAttributesTest < ActiveSupport::TestCase
+  test "product_attributes are read correctly" do
+    params = {
+      order_items_attributes: [
+        {
+          count: "5",
+          product_attributes: {
+            id: products(:fanta).id
+          }
+        }
+      ]
+    }
+
+    o = Order.create(params)
+
+    assert_equal o.order_items.first.product, products(:fanta)
+  end
+end