Fix expense to be nullable without raw material.

internal/validator/purchase_order_validator_test.go

@@ -11,16 +11,20 @@ import (
 )
 
 func validCreatePurchaseOrderRequest() *contract.CreatePurchaseOrderRequest {
+	ingredientID := uuid.New()
+	quantity := 1.0
+	unitID := uuid.New()
+
 	return &contract.CreatePurchaseOrderRequest{
 		VendorID:        uuid.New(),
 		PONumber:        "PO-001",
 		TransactionDate: "2026-05-29",
 		Items: []contract.CreatePurchaseOrderItemRequest{
 			{
-				IngredientID:       uuid.New(),
+				IngredientID:       &ingredientID,
 				PurchaseCategoryID: uuid.New(),
-				Quantity:           1,
-				UnitID:             uuid.New(),
+				Quantity:           &quantity,
+				UnitID:             &unitID,
 				Amount:             1000,
 			},
 		},