test: use fixtures for sales and purchase invoice
diff --git a/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py b/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
index 8aa1f4c..442dc99 100644
--- a/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
+++ b/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
@@ -6,7 +6,7 @@
 
 import frappe
 from frappe.model.dynamic_links import get_dynamic_link_map
-from frappe.tests.utils import change_settings
+from frappe.tests.utils import FrappeTestCase, change_settings
 from frappe.utils import add_days, flt, getdate, nowdate, today
 
 import erpnext
@@ -45,7 +45,7 @@
 from erpnext.stock.utils import get_incoming_rate, get_stock_balance
 
 
-class TestSalesInvoice(unittest.TestCase):
+class TestSalesInvoice(FrappeTestCase):
 	def setUp(self):
 		from erpnext.stock.doctype.stock_ledger_entry.test_stock_ledger_entry import create_items
 
@@ -53,6 +53,9 @@
 		create_internal_parties()
 		setup_accounts()
 
+	def tearDown(self):
+		frappe.db.rollback()
+
 	def make(self):
 		w = frappe.copy_doc(test_records[0])
 		w.is_pos = 0