fix(inventory): update reservation quantity (#10139)

.changeset/curvy-spies-design.md

@@ -0,0 +1,5 @@
+---
+"@medusajs/inventory": patch
+---
+
+Update reservation quantity

packages/modules/inventory/integration-tests/__tests__/inventory-module-service.spec.ts

@@ -399,6 +399,15 @@ moduleIntegrationTestRunner<IInventoryService>({
           const updated = await service.updateReservationItems(update)
 
           expect(updated).toEqual(expect.objectContaining(update))
+
+          const update2 = {
+            id: reservationItem.id,
+            quantity: 10,
+          }
+
+          const updated2 = await service.updateReservationItems(update2)
+
+          expect(updated2).toEqual(expect.objectContaining(update2))
         })
 
         it("should adjust reserved_quantity of inventory level after updates increasing reserved quantity", async () => {
@@ -438,7 +447,7 @@ moduleIntegrationTestRunner<IInventoryService>({
         it("should throw error when increasing reserved quantity beyond availability", async () => {
           const update = {
             id: reservationItem.id,
-            quantity: 10,
+            quantity: 11,
           }
 
           const error = await service

packages/modules/inventory/src/services/inventory-module.ts

@@ -746,10 +746,18 @@ export default class InventoryModuleService
     const availabilityData = input.map((data) => {
       const reservation = reservationMap.get(data.id)!
 
+      let adjustment = data.quantity
+        ? MathBN.sub(data.quantity, reservation.quantity)
+        : 0
+
+      if (MathBN.lt(adjustment, 0)) {
+        adjustment = 0
+      }
+
       return {
         inventory_item_id: reservation.inventory_item_id,
         location_id: data.location_id ?? reservation.location_id,
-        quantity: data.quantity ?? reservation.quantity,
+        quantity: adjustment,
         allow_backorder:
           data.allow_backorder || reservation.allow_backorder || false,
       }