Stock validator test

test/integration/stock_validator_test.rb

@@ -0,0 +1,12 @@
+require 'test_helper'
+
+class StockValidatorTest < ActiveSupport::TestCase
+  test "form gives error when product out of stock" do
+    order = users(:benji).orders.build
+    order.order_items.build(product: products(:cola), count: 10)
+
+    order.save
+
+    assert_includes order.errors[:base], "There is not enough stock for your order of the following products: Cola"
+  end
+end