diff --git a/erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py b/erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py
index c950626..f68122d 100644
--- a/erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py
+++ b/erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py
@@ -13,6 +13,7 @@
 from erpnext.accounts.doctype.payment_entry.payment_entry import get_payment_entry
 from erpnext.buying.doctype.supplier.test_supplier import create_supplier
 from erpnext.controllers.accounts_controller import get_payment_terms
+from erpnext.controllers.buying_controller import QtyMismatchError
 from erpnext.exceptions import InvalidCurrency
 from erpnext.projects.doctype.project.test_project import make_project
 from erpnext.stock.doctype.item.test_item import create_item
@@ -21,7 +22,6 @@
 	make_purchase_receipt,
 )
 from erpnext.stock.doctype.stock_entry.test_stock_entry import get_qty_after_transaction
-from erpnext.controllers.buying_controller import QtyMismatchError
 
 test_dependencies = ["Item", "Cost Center", "Payment Term", "Payment Terms Template"]
 test_ignore = ["Serial No"]
diff --git a/erpnext/controllers/buying_controller.py b/erpnext/controllers/buying_controller.py
index d0defcc..a3d2502 100644
--- a/erpnext/controllers/buying_controller.py
+++ b/erpnext/controllers/buying_controller.py
@@ -3,7 +3,7 @@
 
 
 import frappe
-from frappe import _, msgprint, ValidationError
+from frappe import ValidationError, _, msgprint
 from frappe.contacts.doctype.address.address import get_address_display
 from frappe.utils import cint, cstr, flt, getdate
 
@@ -16,7 +16,9 @@
 from erpnext.stock.get_item_details import get_conversion_factor
 from erpnext.stock.utils import get_incoming_rate
 
-class QtyMismatchError(ValidationError): pass
+
+class QtyMismatchError(ValidationError):
+	pass
 
 class BuyingController(StockController, Subcontracting):
 
diff --git a/erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py b/erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py
index 8968b18..2909a2d 100644
--- a/erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py
+++ b/erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py
@@ -10,12 +10,12 @@
 
 import erpnext
 from erpnext.accounts.doctype.account.test_account import get_inventory_account
+from erpnext.controllers.buying_controller import QtyMismatchError
 from erpnext.stock.doctype.item.test_item import create_item, make_item
 from erpnext.stock.doctype.purchase_receipt.purchase_receipt import make_purchase_invoice
 from erpnext.stock.doctype.serial_no.serial_no import SerialNoDuplicateError, get_serial_nos
 from erpnext.stock.doctype.warehouse.test_warehouse import create_warehouse
 from erpnext.stock.stock_ledger import SerialNoExistsInFutureTransaction
-from erpnext.controllers.buying_controller import QtyMismatchError
 from erpnext.tests.utils import ERPNextTestCase
 
 
@@ -28,8 +28,13 @@
 			1. Test if received qty is validated against accepted + rejected
 			2. Test if received qty is auto set on save
 		"""
-		pr = make_purchase_receipt(qty=1, rejected_qty=1, received_qty=3,
-			item_code="_Test Item Home Desktop 200", do_not_save=True)
+		pr = make_purchase_receipt(
+			qty=1,
+			rejected_qty=1,
+			received_qty=3,
+			item_code="_Test Item Home Desktop 200",
+			do_not_save=True
+		)
 		self.assertRaises(QtyMismatchError, pr.save)
 
 		pr.items[0].received_qty = 0
@@ -43,16 +48,29 @@
 
 		pr = make_purchase_receipt(qty=0.5, item_code="_Test Item Home Desktop 200")
 
-		sl_entry = frappe.db.get_all("Stock Ledger Entry", {"voucher_type": "Purchase Receipt",
-			"voucher_no": pr.name}, ['actual_qty'])
+		sl_entry = frappe.db.get_all(
+			"Stock Ledger Entry",
+			{
+				"voucher_type": "Purchase Receipt",
+				"voucher_no": pr.name
+			},
+			['actual_qty']
+		)
 
 		self.assertEqual(len(sl_entry), 1)
 		self.assertEqual(sl_entry[0].actual_qty, 0.5)
 
 		pr.cancel()
 
-		sl_entry_cancelled = frappe.db.get_all("Stock Ledger Entry", {"voucher_type": "Purchase Receipt",
-			"voucher_no": pr.name}, ['actual_qty'], order_by='creation')
+		sl_entry_cancelled = frappe.db.get_all(
+			"Stock Ledger Entry",
+			{
+				"voucher_type": "Purchase Receipt",
+				"voucher_no": pr.name
+			},
+			['actual_qty'],
+			order_by='creation'
+		)
 
 		self.assertEqual(len(sl_entry_cancelled), 2)
 		self.assertEqual(sl_entry_cancelled[1].actual_qty, -0.5)
@@ -78,8 +96,15 @@
 					}]
 			}).insert()
 
-		template = frappe.db.get_value('Payment Terms Template', '_Test Payment Terms Template For Purchase Invoice')
-		old_template_in_supplier = frappe.db.get_value("Supplier", "_Test Supplier", "payment_terms")
+		template = frappe.db.get_value(
+			"Payment Terms Template",
+			"_Test Payment Terms Template For Purchase Invoice"
+		)
+		old_template_in_supplier = frappe.db.get_value(
+			"Supplier",
+			"_Test Supplier",
+			"payment_terms"
+		)
 		frappe.db.set_value("Supplier", "_Test Supplier", "payment_terms", template)
 
 		pr = make_purchase_receipt(do_not_save=True)
@@ -105,30 +130,59 @@
 		# teardown
 		pi.delete() # draft PI
 		pr.cancel()
-		frappe.db.set_value("Supplier", "_Test Supplier", "payment_terms", old_template_in_supplier)
-		frappe.get_doc('Payment Terms Template', '_Test Payment Terms Template For Purchase Invoice').delete()
+		frappe.db.set_value(
+			"Supplier",
+			"_Test Supplier",
+			"payment_terms",
+			old_template_in_supplier
+		)
+		frappe.get_doc(
+			"Payment Terms Template",
+			"_Test Payment Terms Template For Purchase Invoice"
+		).delete()
 
 	def test_purchase_receipt_no_gl_entry(self):
 		from erpnext.stock.doctype.stock_entry.test_stock_entry import make_stock_entry
 
-		company = frappe.db.get_value('Warehouse', '_Test Warehouse - _TC', 'company')
-
-		existing_bin_qty, existing_bin_stock_value = frappe.db.get_value("Bin", {"item_code": "_Test Item",
-			"warehouse": "_Test Warehouse - _TC"}, ["actual_qty", "stock_value"])
+		existing_bin_qty, existing_bin_stock_value = frappe.db.get_value(
+			"Bin",
+			{
+				"item_code": "_Test Item",
+				"warehouse": "_Test Warehouse - _TC"
+			},
+			["actual_qty", "stock_value"]
+		)
 
 		if existing_bin_qty < 0:
-			make_stock_entry(item_code="_Test Item", target="_Test Warehouse - _TC", qty=abs(existing_bin_qty))
+			make_stock_entry(
+				item_code="_Test Item",
+				target="_Test Warehouse - _TC",
+				qty=abs(existing_bin_qty)
+			)
 
 		pr = make_purchase_receipt()
 
-		stock_value_difference = frappe.db.get_value("Stock Ledger Entry",
-			{"voucher_type": "Purchase Receipt", "voucher_no": pr.name,
-				"item_code": "_Test Item", "warehouse": "_Test Warehouse - _TC"}, "stock_value_difference")
+		stock_value_difference = frappe.db.get_value(
+			"Stock Ledger Entry",
+			{
+				"voucher_type": "Purchase Receipt",
+				"voucher_no": pr.name,
+				"item_code": "_Test Item",
+				"warehouse": "_Test Warehouse - _TC"
+			},
+			"stock_value_difference"
+		)
 
 		self.assertEqual(stock_value_difference, 250)
 
-		current_bin_stock_value = frappe.db.get_value("Bin", {"item_code": "_Test Item",
-			"warehouse": "_Test Warehouse - _TC"}, "stock_value")
+		current_bin_stock_value = frappe.db.get_value(
+			"Bin",
+			{
+				"item_code": "_Test Item",
+				"warehouse": "_Test Warehouse - _TC"
+			},
+			"stock_value"
+		)
 		self.assertEqual(current_bin_stock_value, existing_bin_stock_value + 250)
 
 		self.assertFalse(get_gl_entries("Purchase Receipt", pr.name))
@@ -150,13 +204,17 @@
 
 		pr = make_purchase_receipt(item_code=item.name, qty=5, rate=500)
 
-		self.assertTrue(frappe.db.get_value('Batch', {'item': item.name, 'reference_name': pr.name}))
+		self.assertTrue(
+			frappe.db.get_value('Batch', {'item': item.name, 'reference_name': pr.name})
+		)
 
 		pr.load_from_db()
 		batch_no = pr.items[0].batch_no
 		pr.cancel()
 
-		self.assertFalse(frappe.db.get_value('Batch', {'item': item.name, 'reference_name': pr.name}))
+		self.assertFalse(
+			frappe.db.get_value('Batch', {'item': item.name, 'reference_name': pr.name})
+		)
 		self.assertFalse(frappe.db.get_all('Serial No', {'batch_no': batch_no}))
 
 	def test_duplicate_serial_nos(self):
@@ -175,42 +233,78 @@
 		pr = make_purchase_receipt(item_code=item.name, qty=2, rate=500)
 		pr.load_from_db()
 
-		serial_nos = frappe.db.get_value('Stock Ledger Entry',
-			{'voucher_type': 'Purchase Receipt', 'voucher_no': pr.name, 'item_code': item.name}, 'serial_no')
+		serial_nos = frappe.db.get_value(
+			"Stock Ledger Entry",
+			{
+				"voucher_type": "Purchase Receipt",
+				"voucher_no": pr.name,
+				"item_code": item.name
+			},
+			"serial_no"
+		)
 
 		serial_nos = get_serial_nos(serial_nos)
 
 		self.assertEquals(get_serial_nos(pr.items[0].serial_no), serial_nos)
 
 		# Then tried to receive same serial nos in difference company
-		pr_different_company = make_purchase_receipt(item_code=item.name, qty=2, rate=500,
-			serial_no='\n'.join(serial_nos), company='_Test Company 1', do_not_submit=True,
-			warehouse = 'Stores - _TC1')
+		pr_different_company = make_purchase_receipt(
+			item_code=item.name,
+			qty=2,
+			rate=500,
+			serial_no='\n'.join(serial_nos),
+			company='_Test Company 1',
+			do_not_submit=True,
+			warehouse = 'Stores - _TC1'
+		)
 
 		self.assertRaises(SerialNoDuplicateError, pr_different_company.submit)
 
 		# Then made delivery note to remove the serial nos from stock
-		dn = create_delivery_note(item_code=item.name, qty=2, rate = 1500, serial_no='\n'.join(serial_nos))
+		dn = create_delivery_note(
+			item_code=item.name,
+			qty=2,
+			rate=1500,
+			serial_no='\n'.join(serial_nos)
+		)
 		dn.load_from_db()
 		self.assertEquals(get_serial_nos(dn.items[0].serial_no), serial_nos)
 
 		posting_date = add_days(today(), -3)
 
 		# Try to receive same serial nos again in the same company with backdated.
-		pr1 = make_purchase_receipt(item_code=item.name, qty=2, rate=500,
-			posting_date=posting_date, serial_no='\n'.join(serial_nos), do_not_submit=True)
+		pr1 = make_purchase_receipt(
+			item_code=item.name,
+			qty=2,
+			rate=500,
+			posting_date=posting_date,
+			serial_no='\n'.join(serial_nos),
+			do_not_submit=True
+		)
 
 		self.assertRaises(SerialNoExistsInFutureTransaction, pr1.submit)
 
 		# Try to receive same serial nos with different company with backdated.
-		pr2 = make_purchase_receipt(item_code=item.name, qty=2, rate=500,
-			posting_date=posting_date, serial_no='\n'.join(serial_nos), company='_Test Company 1', do_not_submit=True,
-			warehouse = 'Stores - _TC1')
+		pr2 = make_purchase_receipt(
+			item_code=item.name,
+			qty=2,
+			rate=500,
+			posting_date=posting_date,
+			serial_no='\n'.join(serial_nos),
+			company="_Test Company 1",
+			do_not_submit=True,
+			warehouse="Stores - _TC1"
+		)
 
 		self.assertRaises(SerialNoExistsInFutureTransaction, pr2.submit)
 
 		# Receive the same serial nos after the delivery note posting date and time
-		make_purchase_receipt(item_code=item.name, qty=2, rate=500, serial_no='\n'.join(serial_nos))
+		make_purchase_receipt(
+			item_code=item.name,
+			qty=2,
+			rate=500,
+			serial_no='\n'.join(serial_nos)
+		)
 
 		# Raise the error for backdated deliver note entry cancel
 		self.assertRaises(SerialNoExistsInFutureTransaction, dn.cancel)
@@ -253,11 +347,23 @@
 	def test_subcontracting(self):
 		from erpnext.stock.doctype.stock_entry.test_stock_entry import make_stock_entry
 
-		frappe.db.set_value("Buying Settings", None, "backflush_raw_materials_of_subcontract_based_on", "BOM")
-		make_stock_entry(item_code="_Test Item", target="_Test Warehouse 1 - _TC", qty=100, basic_rate=100)
-		make_stock_entry(item_code="_Test Item Home Desktop 100", target="_Test Warehouse 1 - _TC",
-			qty=100, basic_rate=100)
-		pr = make_purchase_receipt(item_code="_Test FG Item", qty=10, rate=500, is_subcontracted="Yes")
+		frappe.db.set_value(
+			"Buying Settings", None,
+			"backflush_raw_materials_of_subcontract_based_on", "BOM"
+		)
+
+		make_stock_entry(
+			item_code="_Test Item", qty=100,
+			target="_Test Warehouse 1 - _TC", basic_rate=100
+		)
+		make_stock_entry(
+			item_code="_Test Item Home Desktop 100", qty=100,
+			target="_Test Warehouse 1 - _TC", basic_rate=100
+		)
+		pr = make_purchase_receipt(
+			item_code="_Test FG Item", qty=10,
+			rate=500, is_subcontracted="Yes"
+		)
 		self.assertEqual(len(pr.get("supplied_items")), 2)
 
 		rm_supp_cost = sum(d.amount for d in pr.get("supplied_items"))
@@ -267,17 +373,33 @@
 
 	def test_subcontracting_gle_fg_item_rate_zero(self):
 		from erpnext.stock.doctype.stock_entry.test_stock_entry import make_stock_entry
-		frappe.db.set_value("Buying Settings", None, "backflush_raw_materials_of_subcontract_based_on", "BOM")
+		frappe.db.set_value(
+			"Buying Settings", None,
+			"backflush_raw_materials_of_subcontract_based_on", "BOM"
+		)
 
-		se1 = make_stock_entry(item_code="_Test Item", target="Work In Progress - TCP1",
-			qty=100, basic_rate=100, company="_Test Company with perpetual inventory")
+		se1 = make_stock_entry(
+			item_code="_Test Item",
+			target="Work In Progress - TCP1",
+			qty=100, basic_rate=100,
+			company="_Test Company with perpetual inventory"
+		)
 
-		se2 = make_stock_entry(item_code="_Test Item Home Desktop 100", target="Work In Progress - TCP1",
-			qty=100, basic_rate=100, company="_Test Company with perpetual inventory")
+		se2 = make_stock_entry(
+			item_code="_Test Item Home Desktop 100",
+			target="Work In Progress - TCP1",
+			qty=100, basic_rate=100,
+			company="_Test Company with perpetual inventory"
+		)
 
-		pr = make_purchase_receipt(item_code="_Test FG Item", qty=10, rate=0, is_subcontracted="Yes",
-			company="_Test Company with perpetual inventory", warehouse='Stores - TCP1',
-			supplier_warehouse='Work In Progress - TCP1')
+		pr = make_purchase_receipt(
+			item_code="_Test FG Item",
+			qty=10, rate=0,
+			is_subcontracted="Yes",
+			company="_Test Company with perpetual inventory",
+			warehouse="Stores - TCP1",
+			supplier_warehouse="Work In Progress - TCP1"
+		)
 
 		gl_entries = get_gl_entries("Purchase Receipt", pr.name)
 
@@ -311,13 +433,23 @@
 		po = create_purchase_order(item_code=item_code, qty=1, include_exploded_items=0,
 			is_subcontracted="Yes", supplier_warehouse="_Test Warehouse 1 - _TC")
 
-		#stock raw materials in a warehouse before transfer
-		se1 = make_stock_entry(target="_Test Warehouse - _TC",
-			item_code = "Test Extra Item 1", qty=10, basic_rate=100)
-		se2 = make_stock_entry(target="_Test Warehouse - _TC",
-			item_code = "_Test FG Item", qty=1, basic_rate=100)
-		se3 = make_stock_entry(target="_Test Warehouse - _TC",
-			item_code = "Test Extra Item 2", qty=1, basic_rate=100)
+		# stock raw materials in a warehouse before transfer
+		make_stock_entry(
+			target="_Test Warehouse - _TC",
+			item_code = "Test Extra Item 1",
+			qty=10, basic_rate=100
+		)
+		make_stock_entry(
+			target="_Test Warehouse - _TC",
+			item_code = "_Test FG Item",
+			qty=1, basic_rate=100
+		)
+		make_stock_entry(
+			target="_Test Warehouse - _TC",
+			item_code = "Test Extra Item 2",
+			qty=1, basic_rate=100
+		)
+
 		rm_items = [
 			{
 				"item_code": item_code,
@@ -351,11 +483,17 @@
 
 	def test_serial_no_supplier(self):
 		pr = make_purchase_receipt(item_code="_Test Serialized Item With Series", qty=1)
-		self.assertEqual(frappe.db.get_value("Serial No", pr.get("items")[0].serial_no, "supplier"),
-			pr.supplier)
+		pr_row_1_serial_no = pr.get("items")[0].serial_no
+
+		self.assertEqual(
+			frappe.db.get_value("Serial No", pr_row_1_serial_no, "supplier"),
+			pr.supplier
+		)
 
 		pr.cancel()
-		self.assertFalse(frappe.db.get_value("Serial No", pr.get("items")[0].serial_no, "warehouse"))
+		self.assertFalse(
+			frappe.db.get_value("Serial No", pr_row_1_serial_no, "warehouse")
+		)
 
 	def test_rejected_serial_no(self):
 		pr = frappe.copy_doc(test_records[0])
@@ -382,18 +520,33 @@
 		pr.cancel()
 
 	def test_purchase_return_partial(self):
-		pr = make_purchase_receipt(company="_Test Company with perpetual inventory",
-			warehouse = "Stores - TCP1", supplier_warehouse = "Work in Progress - TCP1")
+		pr = make_purchase_receipt(
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			supplier_warehouse = "Work in Progress - TCP1"
+		)
 
-		return_pr = make_purchase_receipt(company="_Test Company with perpetual inventory",
-			warehouse = "Stores - TCP1", supplier_warehouse = "Work in Progress - TCP1",
-			is_return=1, return_against=pr.name, qty=-2, do_not_submit=1)
+		return_pr = make_purchase_receipt(
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			supplier_warehouse = "Work in Progress - TCP1",
+			is_return=1,
+			return_against=pr.name,
+			qty=-2,
+			do_not_submit=1
+		)
 		return_pr.items[0].purchase_receipt_item = pr.items[0].name
 		return_pr.submit()
 
 		# check sle
-		outgoing_rate = frappe.db.get_value("Stock Ledger Entry", {"voucher_type": "Purchase Receipt",
-			"voucher_no": return_pr.name}, "outgoing_rate")
+		outgoing_rate = frappe.db.get_value(
+			"Stock Ledger Entry",
+			{
+				"voucher_type": "Purchase Receipt",
+				"voucher_no": return_pr.name
+			},
+			"outgoing_rate"
+		)
 
 		self.assertEqual(outgoing_rate, 50)
 
@@ -457,11 +610,21 @@
 		pr.cancel()
 
 	def test_purchase_return_full(self):
-		pr = make_purchase_receipt(company="_Test Company with perpetual inventory", warehouse = "Stores - TCP1",
-			supplier_warehouse = "Work in Progress - TCP1")
+		pr = make_purchase_receipt(
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			supplier_warehouse = "Work in Progress - TCP1"
+		)
 
-		return_pr = make_purchase_receipt(company="_Test Company with perpetual inventory", warehouse = "Stores - TCP1",
-			supplier_warehouse = "Work in Progress - TCP1", is_return=1, return_against=pr.name, qty=-5, do_not_submit=1)
+		return_pr = make_purchase_receipt(
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			supplier_warehouse = "Work in Progress - TCP1",
+			is_return=1,
+			return_against=pr.name,
+			qty=-5,
+			do_not_submit=1
+		)
 		return_pr.items[0].purchase_receipt_item = pr.items[0].name
 		return_pr.submit()
 
@@ -483,15 +646,41 @@
 
 		rejected_warehouse="_Test Rejected Warehouse - TCP1"
 		if not frappe.db.exists("Warehouse", rejected_warehouse):
-			get_warehouse(company = "_Test Company with perpetual inventory",
-				abbr = " - TCP1", warehouse_name = "_Test Rejected Warehouse").name
+			get_warehouse(
+				company = "_Test Company with perpetual inventory",
+				abbr = " - TCP1",
+				warehouse_name = "_Test Rejected Warehouse"
+			).name
 
-		pr = make_purchase_receipt(company="_Test Company with perpetual inventory", warehouse = "Stores - TCP1", supplier_warehouse = "Work in Progress - TCP1", received_qty=4, qty=2, rejected_warehouse=rejected_warehouse)
+		pr = make_purchase_receipt(
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			supplier_warehouse = "Work in Progress - TCP1",
+			qty=2,
+			rejected_qty=2,
+			rejected_warehouse=rejected_warehouse
+		)
 
-		return_pr = make_purchase_receipt(company="_Test Company with perpetual inventory", warehouse = "Stores - TCP1", supplier_warehouse = "Work in Progress - TCP1", is_return=1, return_against=pr.name, received_qty = -4, qty=-2, rejected_warehouse=rejected_warehouse)
+		return_pr = make_purchase_receipt(
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			supplier_warehouse = "Work in Progress - TCP1",
+			is_return=1,
+			return_against=pr.name,
+			qty=-2,
+			rejected_qty = -2,
+			rejected_warehouse=rejected_warehouse
+		)
 
-		actual_qty = frappe.db.get_value("Stock Ledger Entry", {"voucher_type": "Purchase Receipt",
-			"voucher_no": return_pr.name, 'warehouse': return_pr.items[0].rejected_warehouse}, "actual_qty")
+		actual_qty = frappe.db.get_value(
+			"Stock Ledger Entry",
+			{
+				"voucher_type": "Purchase Receipt",
+				"voucher_no": return_pr.name,
+				"warehouse": return_pr.items[0].rejected_warehouse
+			},
+			"actual_qty"
+		)
 
 		self.assertEqual(actual_qty, -2)
 
@@ -516,8 +705,13 @@
 			"purchase_document_no": pr.name
 		})
 
-		return_pr = make_purchase_receipt(item_code="_Test Serialized Item With Series", qty=-1,
-			is_return=1, return_against=pr.name, serial_no=serial_no)
+		return_pr = make_purchase_receipt(
+			item_code="_Test Serialized Item With Series",
+			qty=-1,
+			is_return=1,
+			return_against=pr.name,
+			serial_no=serial_no
+		)
 
 		_check_serial_no_values(serial_no, {
 			"warehouse": "",
@@ -539,9 +733,21 @@
 			})
 			row.db_update()
 
-		pr = make_purchase_receipt(item_code=item_code, qty=1, uom="Box", conversion_factor=1.0)
-		return_pr = make_purchase_receipt(item_code=item_code, qty=-10, uom="Unit",
-			stock_uom="Box", conversion_factor=0.1, is_return=1, return_against=pr.name)
+		pr = make_purchase_receipt(
+			item_code=item_code,
+			qty=1,
+			uom="Box",
+			conversion_factor=1.0
+		)
+		return_pr = make_purchase_receipt(
+			item_code=item_code,
+			qty=-10,
+			uom="Unit",
+			stock_uom="Box",
+			conversion_factor=0.1,
+			is_return=1,
+			return_against=pr.name
+		)
 
 		self.assertEqual(abs(return_pr.items[0].stock_qty), 1.0)
 
@@ -557,13 +763,19 @@
 		pr.submit()
 
 		update_purchase_receipt_status(pr.name, "Closed")
-		self.assertEqual(frappe.db.get_value("Purchase Receipt", pr.name, "status"), "Closed")
+		self.assertEqual(
+			frappe.db.get_value("Purchase Receipt", pr.name, "status"), "Closed"
+		)
 
 		pr.reload()
 		pr.cancel()
 
 	def test_pr_billing_status(self):
-		# PO -> PR1 -> PI and PO -> PI and PO -> PR2
+		"""Flow:
+			1. PO -> PR1 -> PI
+			2. PO -> PI
+			3. PO -> PR2.
+		"""
 		from erpnext.buying.doctype.purchase_order.purchase_order import (
 			make_purchase_invoice as make_purchase_invoice_from_po,
 		)
@@ -627,21 +839,39 @@
 		pr_doc = make_purchase_receipt(item_code=item_code,
 			qty=1, serial_no = serial_no)
 
-		self.assertEqual(serial_no, frappe.db.get_value("Serial No",
-			{"purchase_document_type": "Purchase Receipt", "purchase_document_no": pr_doc.name}, "name"))
+		self.assertEqual(
+			serial_no,
+			frappe.db.get_value(
+				"Serial No",
+				{
+					"purchase_document_type": "Purchase Receipt",
+					"purchase_document_no": pr_doc.name
+				},
+				"name"
+			)
+		)
 
 		pr_doc.cancel()
 
-		#check for the auto created serial nos
+		# check for the auto created serial nos
 		item_code = "Test Auto Created Serial No"
 		if not frappe.db.exists("Item", item_code):
-			item = make_item(item_code, dict(has_serial_no=1, serial_no_series="KLJL.###"))
+			make_item(item_code, dict(has_serial_no=1, serial_no_series="KLJL.###"))
 
 		new_pr_doc = make_purchase_receipt(item_code=item_code, qty=1)
 
 		serial_no = get_serial_nos(new_pr_doc.items[0].serial_no)[0]
-		self.assertEqual(serial_no, frappe.db.get_value("Serial No",
-			{"purchase_document_type": "Purchase Receipt", "purchase_document_no": new_pr_doc.name}, "name"))
+		self.assertEqual(
+			serial_no,
+			frappe.db.get_value(
+				"Serial No",
+				{
+					"purchase_document_type": "Purchase Receipt",
+					"purchase_document_no": new_pr_doc.name
+				},
+				"name"
+			)
+		)
 
 		new_pr_doc.cancel()
 
@@ -717,8 +947,12 @@
 
 	def test_purchase_receipt_cost_center(self):
 		from erpnext.accounts.doctype.cost_center.test_cost_center import create_cost_center
+
 		cost_center = "_Test Cost Center for BS Account - TCP1"
-		create_cost_center(cost_center_name="_Test Cost Center for BS Account", company="_Test Company with perpetual inventory")
+		create_cost_center(
+			cost_center_name="_Test Cost Center for BS Account",
+			company="_Test Company with perpetual inventory"
+		)
 
 		if not frappe.db.exists('Location', 'Test Location'):
 			frappe.get_doc({
@@ -726,10 +960,16 @@
 				'location_name': 'Test Location'
 			}).insert()
 
-		pr = make_purchase_receipt(cost_center=cost_center, company="_Test Company with perpetual inventory",
-			warehouse = "Stores - TCP1", supplier_warehouse = "Work in Progress - TCP1")
+		pr = make_purchase_receipt(
+			cost_center=cost_center,
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			supplier_warehouse = "Work in Progress - TCP1"
+		)
 
-		stock_in_hand_account = get_inventory_account(pr.company, pr.get("items")[0].warehouse)
+		stock_in_hand_account = get_inventory_account(
+			pr.company, pr.get("items")[0].warehouse
+		)
 		gl_entries = get_gl_entries("Purchase Receipt", pr.name)
 
 		self.assertTrue(gl_entries)
@@ -753,9 +993,16 @@
 				'doctype': 'Location',
 				'location_name': 'Test Location'
 			}).insert()
-		pr = make_purchase_receipt(company="_Test Company with perpetual inventory", warehouse = "Stores - TCP1", supplier_warehouse = "Work in Progress - TCP1")
 
-		stock_in_hand_account = get_inventory_account(pr.company, pr.get("items")[0].warehouse)
+		pr = make_purchase_receipt(
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			supplier_warehouse = "Work in Progress - TCP1"
+		)
+
+		stock_in_hand_account = get_inventory_account(
+			pr.company, pr.get("items")[0].warehouse
+		)
 		gl_entries = get_gl_entries("Purchase Receipt", pr.name)
 
 		self.assertTrue(gl_entries)
@@ -783,7 +1030,11 @@
 		po = create_purchase_order()
 		pr = create_pr_against_po(po.name)
 
-		pr1 = make_purchase_receipt(is_return=1, return_against=pr.name, qty=-1, do_not_submit=True)
+		pr1 = make_purchase_receipt(
+			qty=-1,
+			is_return=1, return_against=pr.name,
+			do_not_submit=True
+		)
 		pr1.items[0].purchase_order = po.name
 		pr1.items[0].purchase_order_item = po.items[0].name
 		pr1.items[0].purchase_receipt_item = pr.items[0].name
@@ -816,7 +1067,11 @@
 		pi1.save()
 		pi1.submit()
 
-		pr2 = make_purchase_receipt(is_return=1, return_against=pr1.name, qty=-2, do_not_submit=True)
+		pr2 = make_purchase_receipt(
+			qty=-2,
+			is_return=1, return_against=pr1.name,
+			do_not_submit=True
+		)
 		pr2.items[0].purchase_receipt_item = pr1.items[0].name
 		pr2.submit()
 
@@ -858,14 +1113,22 @@
 		pr1.cancel()
 
 	def test_stock_transfer_from_purchase_receipt_with_valuation(self):
-		create_warehouse("_Test Warehouse for Valuation", company="_Test Company with perpetual inventory",
-			properties={"account": '_Test Account Stock In Hand - TCP1'})
+		create_warehouse(
+			"_Test Warehouse for Valuation",
+			company="_Test Company with perpetual inventory",
+			properties={"account": '_Test Account Stock In Hand - TCP1'}
+		)
 
-		pr1 = make_purchase_receipt(warehouse = '_Test Warehouse for Valuation - TCP1',
-			company="_Test Company with perpetual inventory")
+		pr1 = make_purchase_receipt(
+			warehouse = '_Test Warehouse for Valuation - TCP1',
+			company="_Test Company with perpetual inventory"
+		)
 
-		pr = make_purchase_receipt(company="_Test Company with perpetual inventory",
-			warehouse = "Stores - TCP1", do_not_save=1)
+		pr = make_purchase_receipt(
+			company="_Test Company with perpetual inventory",
+			warehouse = "Stores - TCP1",
+			do_not_save=1
+		)
 
 		pr.items[0].from_warehouse = '_Test Warehouse for Valuation - TCP1'
 		pr.supplier_warehouse = ''
@@ -947,10 +1210,24 @@
 		}
 
 		rm_items = [
-			{"item_code":item_code,"rm_item_code":"Sub Contracted Raw Material 3","item_name":"_Test Item",
-				"qty":300,"warehouse":"_Test Warehouse - _TC", "stock_uom":"Nos", "name": po.supplied_items[0].name},
-			{"item_code":item_code,"rm_item_code":"Sub Contracted Raw Material 3","item_name":"_Test Item",
-				"qty":200,"warehouse":"_Test Warehouse - _TC", "stock_uom":"Nos", "name": po.supplied_items[0].name}
+			{
+				"item_code":item_code,
+				"rm_item_code":"Sub Contracted Raw Material 3",
+				"item_name":"_Test Item",
+				"qty":300,
+				"warehouse":"_Test Warehouse - _TC",
+				"stock_uom":"Nos",
+				"name": po.supplied_items[0].name
+			},
+			{
+				"item_code":item_code,
+				"rm_item_code":"Sub Contracted Raw Material 3",
+				"item_name":"_Test Item",
+				"qty":200,
+				"warehouse":"_Test Warehouse - _TC",
+				"stock_uom":"Nos",
+				"name": po.supplied_items[0].name
+			}
 		]
 
 		rm_item_string = json.dumps(rm_items)
@@ -960,8 +1237,14 @@
 		se.items[1].batch_no = ste2.items[0].batch_no
 		se.submit()
 
-		supplied_qty = frappe.db.get_value("Purchase Order Item Supplied",
-			{"parent": po.name, "rm_item_code": "Sub Contracted Raw Material 3"}, "supplied_qty")
+		supplied_qty = frappe.db.get_value(
+			"Purchase Order Item Supplied",
+			{
+				"parent": po.name,
+				"rm_item_code": "Sub Contracted Raw Material 3"
+			},
+			"supplied_qty"
+		)
 
 		self.assertEqual(supplied_qty, 500.00)
 
@@ -1033,10 +1316,18 @@
 		company = '_Test Company with perpetual inventory'
 		service_item = '_Test Non Stock Item'
 
-		before_test_value = frappe.db.get_value('Company', company, 'enable_perpetual_inventory_for_non_stock_items')
-		frappe.db.set_value('Company', company, 'enable_perpetual_inventory_for_non_stock_items', 1)
+		before_test_value = frappe.db.get_value(
+			'Company', company, 'enable_perpetual_inventory_for_non_stock_items'
+		)
+		frappe.db.set_value(
+			'Company', company,
+			'enable_perpetual_inventory_for_non_stock_items', 1
+		)
 		srbnb_account = 'Stock Received But Not Billed - TCP1'
-		frappe.db.set_value('Company', company, 'service_received_but_not_billed', srbnb_account)
+		frappe.db.set_value(
+			'Company', company,
+			'service_received_but_not_billed', srbnb_account
+		)
 
 		pr = make_purchase_receipt(
 			company=company, item=service_item,
@@ -1068,7 +1359,10 @@
 		self.assertEqual(len(item_one_gl_entry), 1)
 		self.assertEqual(len(item_two_gl_entry), 1)
 
-		frappe.db.set_value('Company', company, 'enable_perpetual_inventory_for_non_stock_items', before_test_value)
+		frappe.db.set_value(
+			'Company', company,
+			'enable_perpetual_inventory_for_non_stock_items', before_test_value
+		)
 
 	def test_purchase_receipt_with_exchange_rate_difference(self):
 		from erpnext.accounts.doctype.purchase_invoice.purchase_invoice import (
@@ -1093,10 +1387,19 @@
 		pr.submit()
 
 		# Get exchnage gain and loss account
-		exchange_gain_loss_account = frappe.db.get_value('Company', pr.company, 'exchange_gain_loss_account')
+		exchange_gain_loss_account = frappe.db.get_value(
+			'Company', pr.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': pr.name}, 'credit')
+		amount = frappe.db.get_value(
+			'GL Entry',
+			{
+				'account': exchange_gain_loss_account,
+				'voucher_no': pr.name
+			},
+			'credit'
+		)
 		discrepancy_caused_by_exchange_rate_diff = abs(pi.items[0].base_net_amount - pr.items[0].base_net_amount)
 
 		self.assertEqual(discrepancy_caused_by_exchange_rate_diff, amount)
@@ -1266,9 +1569,12 @@
 
 	if args.get_multiple_items:
 		pr.items = []
-		for item in get_items(warehouse= args.warehouse, cost_center = args.cost_center or frappe.get_cached_value('Company', pr.company, 'cost_center')):
-			pr.append("items", item)
 
+		company_cost_center = frappe.get_cached_value('Company', pr.company, 'cost_center')
+		cost_center = args.cost_center or company_cost_center
+
+		for item in get_items(warehouse=args.warehouse, cost_center=cost_center):
+			pr.append("items", item)
 
 	if args.get_taxes_and_charges:
 		for tax in get_taxes():