fix: missing def expense if no exp in first month (backport #40865)

erpnext/accounts/deferred_revenue.py

@@ -360,45 +360,45 @@ def _book_deferred_revenue_or_expense(
 			)
 
 		if not amount:
-			return
-
-		gl_posting_date = end_date
-		prev_posting_date = None
-		# check if books nor frozen till endate:
-		if accounts_frozen_upto and getdate(end_date) <= getdate(accounts_frozen_upto):
-			gl_posting_date = get_last_day(add_days(accounts_frozen_upto, 1))
 			prev_posting_date = end_date
-
-		if via_journal_entry:
-			book_revenue_via_journal_entry(
-				doc,
-				credit_account,
-				debit_account,
-				amount,
-				base_amount,
-				gl_posting_date,
-				project,
-				account_currency,
-				item.cost_center,
-				item,
-				deferred_process,
-				submit_journal_entry,
-			)
 		else:
-			make_gl_entries(
-				doc,
-				credit_account,
-				debit_account,
-				against,
-				amount,
-				base_amount,
-				gl_posting_date,
-				project,
-				account_currency,
-				item.cost_center,
-				item,
-				deferred_process,
-			)
+			gl_posting_date = end_date
+			prev_posting_date = None
+			# check if books nor frozen till endate:
+			if accounts_frozen_upto and getdate(end_date) <= getdate(accounts_frozen_upto):
+				gl_posting_date = get_last_day(add_days(accounts_frozen_upto, 1))
+				prev_posting_date = end_date
+
+			if via_journal_entry:
+				book_revenue_via_journal_entry(
+					doc,
+					credit_account,
+					debit_account,
+					amount,
+					base_amount,
+					gl_posting_date,
+					project,
+					account_currency,
+					item.cost_center,
+					item,
+					deferred_process,
+					submit_journal_entry,
+				)
+			else:
+				make_gl_entries(
+					doc,
+					credit_account,
+					debit_account,
+					against,
+					amount,
+					base_amount,
+					gl_posting_date,
+					project,
+					account_currency,
+					item.cost_center,
+					item,
+					deferred_process,
+				)
 
 		# Returned in case of any errors because it tries to submit the same record again and again in case of errors
 		if frappe.flags.deferred_accounting_error:

erpnext/accounts/report/deferred_revenue_and_expense/test_deferred_revenue_and_expense.py

@@ -279,3 +279,79 @@ def test_zero_months(self):
 			{"key": "aug_2021", "total": 0, "actual": 0},
 		]
 		self.assertEqual(report.period_total, expected)
+
+	@change_settings(
+		"Accounts Settings",
+		{"book_deferred_entries_based_on": "Months", "book_deferred_entries_via_journal_entry": 0},
+	)
+	def test_zero_amount(self):
+		self.create_item("_Test Office Desk", 0, self.warehouse, self.company)
+		item = frappe.get_doc("Item", self.item)
+		item.enable_deferred_expense = 1
+		item.item_defaults[0].deferred_expense_account = self.deferred_expense_account
+		item.no_of_months_exp = 12
+		item.save()
+
+		pi = make_purchase_invoice(
+			item=self.item,
+			company=self.company,
+			supplier=self.supplier,
+			is_return=False,
+			update_stock=False,
+			posting_date=frappe.utils.datetime.date(2021, 12, 30),
+			parent_cost_center=self.cost_center,
+			cost_center=self.cost_center,
+			do_not_save=True,
+			rate=3910,
+			price_list_rate=3910,
+			warehouse=self.warehouse,
+			qty=1,
+		)
+		pi.set_posting_time = True
+		pi.items[0].enable_deferred_expense = 1
+		pi.items[0].service_start_date = "2021-12-30"
+		pi.items[0].service_end_date = "2022-12-30"
+		pi.items[0].deferred_expense_account = self.deferred_expense_account
+		pi.items[0].expense_account = self.expense_account
+		pi.save()
+		pi.submit()
+
+		pda = frappe.get_doc(
+			doctype="Process Deferred Accounting",
+			posting_date=nowdate(),
+			start_date="2022-01-01",
+			end_date="2022-01-31",
+			type="Expense",
+			company=self.company,
+		)
+		pda.insert()
+		pda.submit()
+
+		# execute report
+		fiscal_year = frappe.get_doc("Fiscal Year", get_fiscal_year(date="2022-01-31"))
+		self.filters = frappe._dict(
+			{
+				"company": self.company,
+				"filter_based_on": "Date Range",
+				"period_start_date": "2022-01-01",
+				"period_end_date": "2022-01-31",
+				"from_fiscal_year": fiscal_year.year,
+				"to_fiscal_year": fiscal_year.year,
+				"periodicity": "Monthly",
+				"type": "Expense",
+				"with_upcoming_postings": False,
+			}
+		)
+
+		report = Deferred_Revenue_and_Expense_Report(filters=self.filters)
+		report.run()
+
+		# fetch the invoice from deferred invoices list
+		inv = [d for d in report.deferred_invoices if d.name == pi.name]
+		# make sure the list isn't empty
+		self.assertTrue(inv)
+		# calculate the total deferred expense for the period
+		inv = inv[0].calculate_invoice_revenue_expense_for_period()
+		deferred_exp = sum([inv[idx].actual for idx in range(len(report.period_list))])
+		# make sure the total deferred expense is greater than 0
+		self.assertLess(deferred_exp, 0)