Fixes for calculating lowest price after refactoring. #375.

Author: Agata Firlejczyk

src/lib/taxcalc.js

@@ -101,11 +101,13 @@ export function updateProductPrices ({ product, rate, sourcePriceInclTax = false
 
   if (product.final_price) {
     if (product.final_price < product.price) { // compare the prices with the product final price if provided; final prices is used in case of active catalog promo rules for example
-      assignPrice({product, target: 'price', price: product.final_price, deprecatedPriceFieldsSupport})
-      if (product.final_price < product.special_price) { // for VS - special_price is any price lowered than regular price (`price`); in Magento there is a separate mechanism for setting the `special_prices`
-        assignPrice({product, target: 'price', price: product.special_price, deprecatedPriceFieldsSupport}) // if the `final_price` is lower than the original `special_price` - it means some catalog rules were applied over it
+      assignPrice({product, target: 'price', ...finalPriceWithTax, deprecatedPriceFieldsSupport})
+      if (product.special_price && product.final_price < product.special_price) { // for VS - special_price is any price lowered than regular price (`price`); in Magento there is a separate mechanism for setting the `special_prices`
+        assignPrice({product, target: 'price', ...specialPriceWithTax, deprecatedPriceFieldsSupport}) // if the `final_price` is lower than the original `special_price` - it means some catalog rules were applied over it
+        assignPrice({product, target: 'special_price', ...finalPriceWithTax, deprecatedPriceFieldsSupport})
+      } else {
+        assignPrice({product, target: 'price', ...finalPriceWithTax, deprecatedPriceFieldsSupport})
       }
-      assignPrice({product, target: 'special_price', price: product.final_price, deprecatedPriceFieldsSupport})
     }
   }