(feat) check order's item amount and quantity min before checkout

app/exceptions/cart/item_amount_error.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+# Raised when the item's amount != product's amount
+class Cart::ItemAmountError < StandardError
+end

app/exceptions/cart/quantity_min_error.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+# Raised when the item's quantity < product's quantity min
+class Cart::QuantityMinError < StandardError
+end

app/services/checkout/payment_service.rb

@@ -11,6 +11,10 @@ class Checkout::PaymentService
 
     raise Cart::OutStockError unless Orders::OrderService.new.in_stock?(order, 'external')
 
+    raise Cart::QuantityMinError unless Orders::OrderService.new.greater_than_quantity_min?(order)
+
+    raise Cart::ItemAmountError unless Orders::OrderService.new.item_amount_not_equal?(order)
+
     CouponService.new.validate(coupon_code, order.statistic_profile.user.id)
 
     amount = debit_amount(order)

app/services/orders/order_service.rb

@@ -58,6 +58,20 @@ class Orders::OrderService
     true
   end
 
+  def greater_than_quantity_min?(order)
+    order.order_items.each do |item|
+      return false if item.quantity < item.orderable.quantity_min
+    end
+    true
+  end
+
+  def item_amount_not_equal?(order)
+    order.order_items.each do |item|
+      return false if item.amount != item.orderable.amount
+    end
+    true
+  end
+
   def all_products_is_active?(order)
     order.order_items.each do |item|
       return false unless item.orderable.is_active