From 7e05bea6a9fd3d2d6402c5e22d11b68e1225a774 Mon Sep 17 00:00:00 2001
From: Afshan <33727827+AfshanKhan@users.noreply.github.com>
Date: Mon, 12 Jul 2021 11:11:58 +0530
Subject: [PATCH] fix: dunning calculation of grand total when rate of interest
 is 0% (#26286)

---
 erpnext/accounts/doctype/dunning/dunning.py   |  8 ++--
 .../accounts/doctype/dunning/test_dunning.py  | 48 ++++++++++++++++++-
 2 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/erpnext/accounts/doctype/dunning/dunning.py b/erpnext/accounts/doctype/dunning/dunning.py
index c6c689212b..1ef512a489 100644
--- a/erpnext/accounts/doctype/dunning/dunning.py
+++ b/erpnext/accounts/doctype/dunning/dunning.py
@@ -25,7 +25,7 @@ class Dunning(AccountsController):
 
 	def validate_amount(self):
 		amounts = calculate_interest_and_amount(
-			self.posting_date, self.outstanding_amount, self.rate_of_interest, self.dunning_fee, self.overdue_days)
+			self.outstanding_amount, self.rate_of_interest, self.dunning_fee, self.overdue_days)
 		if self.interest_amount != amounts.get('interest_amount'):
 			self.interest_amount = flt(amounts.get('interest_amount'), self.precision('interest_amount'))
 		if self.dunning_amount != amounts.get('dunning_amount'):
@@ -91,13 +91,13 @@ def resolve_dunning(doc, state):
 			for dunning in dunnings:
 				frappe.db.set_value("Dunning", dunning.name, "status", 'Resolved')
 
-def calculate_interest_and_amount(posting_date, outstanding_amount, rate_of_interest, dunning_fee, overdue_days):
+def calculate_interest_and_amount(outstanding_amount, rate_of_interest, dunning_fee, overdue_days):
 	interest_amount = 0
-	grand_total = 0
+	grand_total = flt(outstanding_amount) + flt(dunning_fee)
 	if rate_of_interest:
 		interest_per_year = flt(outstanding_amount) * flt(rate_of_interest) / 100
 		interest_amount = (interest_per_year * cint(overdue_days)) / 365
-		grand_total = flt(outstanding_amount) + flt(interest_amount) + flt(dunning_fee)
+		grand_total += flt(interest_amount)
 	dunning_amount = flt(interest_amount) + flt(dunning_fee)
 	return {
 		'interest_amount': interest_amount,
diff --git a/erpnext/accounts/doctype/dunning/test_dunning.py b/erpnext/accounts/doctype/dunning/test_dunning.py
index e2d4d82e41..31cb078cd4 100644
--- a/erpnext/accounts/doctype/dunning/test_dunning.py
+++ b/erpnext/accounts/doctype/dunning/test_dunning.py
@@ -16,6 +16,7 @@ class TestDunning(unittest.TestCase):
 	@classmethod
 	def setUpClass(self):
 		create_dunning_type()
+		create_dunning_type_with_zero_interest_rate()
 		unlink_payment_on_cancel_of_invoice()
 
 	@classmethod
@@ -25,11 +26,19 @@ class TestDunning(unittest.TestCase):
 	def test_dunning(self):
 		dunning = create_dunning()
 		amounts = calculate_interest_and_amount(
-			dunning.posting_date, dunning.outstanding_amount, dunning.rate_of_interest, dunning.dunning_fee, dunning.overdue_days)
+			dunning.outstanding_amount, dunning.rate_of_interest, dunning.dunning_fee, dunning.overdue_days)
 		self.assertEqual(round(amounts.get('interest_amount'), 2), 0.44)
 		self.assertEqual(round(amounts.get('dunning_amount'), 2), 20.44)
 		self.assertEqual(round(amounts.get('grand_total'), 2), 120.44)
 
+	def test_dunning_with_zero_interest_rate(self):
+		dunning = create_dunning_with_zero_interest_rate()
+		amounts = calculate_interest_and_amount(
+			dunning.outstanding_amount, dunning.rate_of_interest, dunning.dunning_fee, dunning.overdue_days)
+		self.assertEqual(round(amounts.get('interest_amount'), 2), 0)
+		self.assertEqual(round(amounts.get('dunning_amount'), 2), 20)
+		self.assertEqual(round(amounts.get('grand_total'), 2), 120)
+
 	def test_gl_entries(self):
 		dunning = create_dunning()
 		dunning.submit()
@@ -83,6 +92,27 @@ def create_dunning():
 	dunning.save()
 	return dunning
 
+def create_dunning_with_zero_interest_rate():
+	posting_date = add_days(today(), -20)
+	due_date = add_days(today(), -15)
+	sales_invoice = create_sales_invoice_against_cost_center(
+		posting_date=posting_date, due_date=due_date, status='Overdue')
+	dunning_type = frappe.get_doc("Dunning Type", 'First Notice with 0% Rate of Interest')
+	dunning = frappe.new_doc("Dunning")
+	dunning.sales_invoice = sales_invoice.name
+	dunning.customer_name = sales_invoice.customer_name
+	dunning.outstanding_amount = sales_invoice.outstanding_amount
+	dunning.debit_to = sales_invoice.debit_to
+	dunning.currency = sales_invoice.currency
+	dunning.company = sales_invoice.company
+	dunning.posting_date = nowdate()
+	dunning.due_date = sales_invoice.due_date
+	dunning.dunning_type = 'First Notice with 0% Rate of Interest'
+	dunning.rate_of_interest = dunning_type.rate_of_interest
+	dunning.dunning_fee = dunning_type.dunning_fee
+	dunning.save()
+	return dunning
+
 def create_dunning_type():
 	dunning_type = frappe.new_doc("Dunning Type")
 	dunning_type.dunning_type = 'First Notice'
@@ -98,3 +128,19 @@ def create_dunning_type():
 		}
 	)
 	dunning_type.save()
+
+def create_dunning_type_with_zero_interest_rate():
+	dunning_type = frappe.new_doc("Dunning Type")
+	dunning_type.dunning_type = 'First Notice with 0% Rate of Interest'
+	dunning_type.start_day = 10
+	dunning_type.end_day = 20
+	dunning_type.dunning_fee = 20
+	dunning_type.rate_of_interest = 0
+	dunning_type.append(
+		"dunning_letter_text", {
+			'language': 'en',
+			'body_text': 'We have still not received payment for our invoice ',
+			'closing_text': 'We kindly request that you pay the outstanding amount immediately, and late fees.'
+		}
+	)
+	dunning_type.save()
\ No newline at end of file