refactor(test): use @change_settings in sales invoice

erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py

@@ -51,14 +51,10 @@ def setUp(self):
 		create_items(["_Test Internal Transfer Item"], uoms=[{"uom": "Box", "conversion_factor": 10}])
 		create_internal_parties()
 		setup_accounts()
-		self.remove_accounts_frozen_date()
 
 	def tearDown(self):
 		frappe.db.rollback()
 
-	def remove_accounts_frozen_date(self):
-		frappe.db.set_single_value("Accounts Settings", "acc_frozen_upto", None)
-
 	def make(self):
 		w = frappe.copy_doc(test_records[0])
 		w.is_pos = 0
@@ -3079,8 +3075,8 @@ def test_sales_commission(self):
 			si.commission_rate = commission_rate
 			self.assertRaises(frappe.ValidationError, si.save)
 
+	@change_settings("Accounts Settings", {"acc_frozen_upto": add_days(getdate(), 1)})
 	def test_sales_invoice_submission_post_account_freezing_date(self):
-		frappe.db.set_single_value("Accounts Settings", "acc_frozen_upto", add_days(getdate(), 1))
 		si = create_sales_invoice(do_not_save=True)
 		si.posting_date = add_days(getdate(), 1)
 		si.save()
@@ -3089,8 +3085,6 @@ def test_sales_invoice_submission_post_account_freezing_date(self):
 		si.posting_date = getdate()
 		si.submit()
 
-		frappe.db.set_single_value("Accounts Settings", "acc_frozen_upto", None)
-
 	def test_over_billing_case_against_delivery_note(self):
 		"""
 		Test a case where duplicating the item with qty = 1 in the invoice
@@ -3119,6 +3113,7 @@ def test_over_billing_case_against_delivery_note(self):
 
 		frappe.db.set_single_value("Accounts Settings", "over_billing_allowance", over_billing_allowance)
 
+	@change_settings("Accounts Settings", {"acc_frozen_upto": getdate("2019-01-31")})
 	def test_multi_currency_deferred_revenue_via_journal_entry(self):
 		deferred_account = create_account(
 			account_name="Deferred Revenue",
@@ -3156,8 +3151,6 @@ def test_multi_currency_deferred_revenue_via_journal_entry(self):
 		si.save()
 		si.submit()
 
-		frappe.db.set_single_value("Accounts Settings", "acc_frozen_upto", getdate("2019-01-31"))
-
 		pda1 = frappe.get_doc(
 			dict(
 				doctype="Process Deferred Accounting",
@@ -3201,8 +3194,6 @@ def test_multi_currency_deferred_revenue_via_journal_entry(self):
 		acc_settings.submit_journal_entries = 0
 		acc_settings.save()
 
-		frappe.db.set_single_value("Accounts Settings", "acc_frozen_upto", None)
-
 	def test_standalone_serial_no_return(self):
 		si = create_sales_invoice(
 			item_code="_Test Serialized Item With Series", update_stock=True, is_return=True, qty=-1