From acf6bbc2ec1d90e3b0100c86f56e96b38fa7c67a Mon Sep 17 00:00:00 2001
From: William Bouchard <46496014+willbouch@users.noreply.github.com>
Date: Tue, 5 Aug 2025 09:01:41 -0400
Subject: [PATCH] chore(core-flows): throw error on invalid promo code (#13140)

* chore(core-flows): throw error on invalid promo code

* add changelog

* better error handling in test

---------

Co-authored-by: william bouchard <williambouchard@williams-MacBook-Pro.local>
Co-authored-by: Carlos R. L. Rodrigues <37986729+carlos-r-l-rodrigues@users.noreply.github.com>
---
 .changeset/ninety-kangaroos-grin.md           |  5 +++
 .../http/__tests__/cart/store/cart.spec.ts    | 18 ++++++++
 .../steps/get-promotion-codes-to-apply.ts     | 45 ++++++++++++++-----
 3 files changed, 57 insertions(+), 11 deletions(-)
 create mode 100644 .changeset/ninety-kangaroos-grin.md

diff --git a/.changeset/ninety-kangaroos-grin.md b/.changeset/ninety-kangaroos-grin.md
new file mode 100644
index 0000000000..3e87bedb27
--- /dev/null
+++ b/.changeset/ninety-kangaroos-grin.md
@@ -0,0 +1,5 @@
+---
+"@medusajs/core-flows": minor
+---
+
+chore(code-flows): throw error on invalid promo code
diff --git a/integration-tests/http/__tests__/cart/store/cart.spec.ts b/integration-tests/http/__tests__/cart/store/cart.spec.ts
index 297b382197..cc58729ebd 100644
--- a/integration-tests/http/__tests__/cart/store/cart.spec.ts
+++ b/integration-tests/http/__tests__/cart/store/cart.spec.ts
@@ -2815,6 +2815,24 @@ medusaIntegrationTestRunner({
           )
         })
 
+        it("should throw an error when adding a promotion that does not exist", async () => {
+          const invalidPromoCode = "SOME_INVALID_PROMO_CODE"
+
+          const { response } = await api
+            .post(
+              `/store/carts/${cart.id}/promotions`,
+              { promo_codes: [invalidPromoCode] },
+              storeHeaders
+            )
+            .catch((e) => e)
+
+          expect(response.status).toEqual(400)
+          expect(response.data.type).toEqual("invalid_data")
+          expect(response.data.message).toEqual(
+            `The promotion code ${invalidPromoCode} is invalid`
+          )
+        })
+
         it("should remove promotion adjustments when promotion is deleted", async () => {
           let cartBeforeRemovingPromotion = (
             await api.get(`/store/carts/${cart.id}`, storeHeaders)
diff --git a/packages/core/core-flows/src/cart/steps/get-promotion-codes-to-apply.ts b/packages/core/core-flows/src/cart/steps/get-promotion-codes-to-apply.ts
index 4de4ab53fb..9b554e707d 100644
--- a/packages/core/core-flows/src/cart/steps/get-promotion-codes-to-apply.ts
+++ b/packages/core/core-flows/src/cart/steps/get-promotion-codes-to-apply.ts
@@ -1,6 +1,10 @@
 import { IPromotionModuleService } from "@medusajs/framework/types"
-import { Modules, PromotionActions } from "@medusajs/framework/utils"
-import { StepResponse, createStep } from "@medusajs/framework/workflows-sdk"
+import {
+  MedusaError,
+  Modules,
+  PromotionActions,
+} from "@medusajs/framework/utils"
+import { createStep, StepResponse } from "@medusajs/framework/workflows-sdk"
 
 /**
  * The details of the promotion codes to apply on a cart.
@@ -68,14 +72,12 @@ export const getPromotionCodesToApply = createStep(
   async (data: GetPromotionCodesToApplyStepInput, { container }) => {
     const { promo_codes = [], cart, action = PromotionActions.ADD } = data
     const { items = [], shipping_methods = [] } = cart
-    const adjustmentCodes: string[] = []
     const promotionService = container.resolve<IPromotionModuleService>(
       Modules.PROMOTION
     )
 
-    const objects = items.concat(shipping_methods)
-
-    objects.forEach((object) => {
+    const adjustmentCodes: string[] = []
+    items.concat(shipping_methods).forEach((object) => {
       object.adjustments?.forEach((adjustment) => {
         if (adjustment.code && !adjustmentCodes.includes(adjustment.code)) {
           adjustmentCodes.push(adjustment.code)
@@ -94,17 +96,38 @@ export const getPromotionCodesToApply = createStep(
         : []
     )
 
-    if (action === PromotionActions.ADD) {
-      promo_codes.forEach((code) => promotionCodesToApply.add(code))
-    }
-
     if (action === PromotionActions.REMOVE) {
       promo_codes.forEach((code) => promotionCodesToApply.delete(code))
     }
 
     if (action === PromotionActions.REPLACE) {
       promotionCodesToApply.clear()
-      promo_codes.forEach((code) => promotionCodesToApply.add(code))
+    }
+
+    if (
+      action === PromotionActions.ADD ||
+      action === PromotionActions.REPLACE
+    ) {
+      const validPromoCodes: Set<string> = new Set(
+        promo_codes.length
+          ? (
+              await promotionService.listPromotions(
+                { code: promo_codes },
+                { select: ["code"] }
+              )
+            ).map((p) => p.code!)
+          : []
+      )
+
+      promo_codes.forEach((code) => {
+        if (!validPromoCodes.has(code)) {
+          throw new MedusaError(
+            MedusaError.Types.INVALID_DATA,
+            `The promotion code ${code} is invalid`
+          )
+        }
+        promotionCodesToApply.add(code)
+      })
     }
 
     return new StepResponse(