require 'test_helper' class StockTest < ActiveSupport::TestCase test "creating and deleting orders updates stock of products" do order = users(:benji).orders.build order.order_items.build(product: products(:fanta), count: 2) assert_difference "products(:fanta).stock", -2 do order.save(validate: false) end assert_difference "products(:fanta).stock", +2 do order.destroy end end end