fix: validate non-stock item for exchange loss/gain (backport #45306) (#45380)

fix: validate non-stock item for exchange loss/gain (#45306)

* fix: validate non-stock item

* test: add unit test to validate non-stock item exchange difference

* fix: use usd supplier

(cherry picked from commit 05579959f2)

Co-authored-by: Rethik M <85231069+rs-rethik@users.noreply.github.com>

erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py

@@ -1126,6 +1126,7 @@ class PurchaseInvoice(BuyingController):
 								exchange_rate_map[item.purchase_receipt]
 								and self.conversion_rate != exchange_rate_map[item.purchase_receipt]
 								and item.net_rate == net_rate_map[item.pr_detail]
+								and item.item_code in stock_items
 							):
 								discrepancy_caused_by_exchange_rate_difference = (
 									item.qty * item.net_rate

erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py

@@ -372,6 +372,53 @@ class TestPurchaseInvoice(FrappeTestCase, StockTestMixin):
 
 		self.assertEqual(discrepancy_caused_by_exchange_rate_diff, amount)
 
+	def test_purchase_invoice_with_exchange_rate_difference_for_non_stock_item(self):
+		from erpnext.stock.doctype.purchase_receipt.purchase_receipt import (
+			make_purchase_invoice as create_purchase_invoice,
+		)
+
+		# Creating Purchase Invoice with USD currency
+		pr = frappe.new_doc("Purchase Receipt")
+		pr.currency = "USD"
+		pr.company = "_Test Company with perpetual inventory"
+		pr.conversion_rate = (70,)
+		pr.supplier = "_Test Supplier USD"
+		pr.append(
+			"items",
+			{
+				"item_code": "_Test Non Stock Item",
+				"qty": 1,
+				"rate": 100,
+			},
+		)
+		pr.append(
+			"items",
+			{"item_code": "_Test Item", "qty": 1, "rate": 5, "warehouse": "Stores - TCP1"},
+		)
+		pr.insert()
+		pr.submit()
+
+		# Createing purchase invoice against Purchase Receipt
+		pi = create_purchase_invoice(pr.name)
+		pi.conversion_rate = 80
+		pi.credit_to = "_Test Payable USD - TCP1"
+		pi.insert()
+		pi.submit()
+
+		# Get exchnage gain and loss account
+		exchange_gain_loss_account = frappe.db.get_value("Company", pi.company, "exchange_gain_loss_account")
+
+		# fetching the latest GL Entry with exchange gain and loss account account
+		amount = frappe.db.get_value(
+			"GL Entry", {"account": exchange_gain_loss_account, "voucher_no": pi.name}, "debit"
+		)
+
+		discrepancy_caused_by_exchange_rate_diff = abs(
+			pi.items[1].base_net_amount - pr.items[1].base_net_amount
+		)
+
+		self.assertEqual(discrepancy_caused_by_exchange_rate_diff, amount)
+
 	def test_purchase_invoice_change_naming_series(self):
 		pi = frappe.copy_doc(test_records[1])
 		pi.insert()