diff --git a/erpnext/accounts/doctype/dunning/test_dunning.py b/erpnext/accounts/doctype/dunning/test_dunning.py
index e1fd1e9..956b1cf 100644
--- a/erpnext/accounts/doctype/dunning/test_dunning.py
+++ b/erpnext/accounts/doctype/dunning/test_dunning.py
@@ -6,7 +6,7 @@
 import frappe
 from frappe.utils import add_days, nowdate, today
 
-from erpnext.accounts.doctype.dunning.dunning import calculate_interest_and_amount
+from erpnext.accounts.doctype.sales_invoice.sales_invoice import create_dunning as create_dunning_from_sales_invoice
 from erpnext.accounts.doctype.payment_entry.test_payment_entry import get_payment_entry
 from erpnext.accounts.doctype.purchase_invoice.test_purchase_invoice import (
 	unlink_payment_on_cancel_of_invoice,
@@ -19,34 +19,34 @@
 class TestDunning(unittest.TestCase):
 	@classmethod
 	def setUpClass(self):
-		create_dunning_type()
-		create_dunning_type_with_zero_interest_rate()
+		create_dunning_type("First Notice", fee=0.0, interest=0.0, is_default=1)
+		create_dunning_type("Second Notice", fee=10.0, interest=10.0, is_default=0)
 		unlink_payment_on_cancel_of_invoice()
 
 	@classmethod
 	def tearDownClass(self):
 		unlink_payment_on_cancel_of_invoice(0)
 
-	def test_dunning(self):
-		dunning = create_dunning()
-		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), 0.44)
-		self.assertEqual(round(amounts.get("dunning_amount"), 2), 20.44)
-		self.assertEqual(round(amounts.get("grand_total"), 2), 120.44)
+	def test_first_dunning(self):
+		dunning = create_first_dunning()
 
-	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)
+		self.assertEqual(round(dunning.total_outstanding, 2), 100.00)
+		self.assertEqual(round(dunning.total_interest, 2), 0.00)
+		self.assertEqual(round(dunning.dunning_fee, 2), 0.00)
+		self.assertEqual(round(dunning.dunning_amount, 2), 0.00)
+		self.assertEqual(round(dunning.grand_total, 2), 100.00)
+
+	def test_second_dunning(self):
+		dunning = create_second_dunning()
+
+		self.assertEqual(round(dunning.total_outstanding, 2), 100.00)
+		self.assertEqual(round(dunning.total_interest, 2), 0.41)
+		self.assertEqual(round(dunning.dunning_fee, 2), 10.00)
+		self.assertEqual(round(dunning.dunning_amount, 2), 10.41)
+		self.assertEqual(round(dunning.grand_total, 2), 110.41)
 
 	def test_gl_entries(self):
-		dunning = create_dunning()
+		dunning = create_second_dunning()
 		dunning.submit()
 		gl_entries = frappe.db.sql(
 			"""select account, debit, credit
@@ -56,16 +56,17 @@
 			as_dict=1,
 		)
 		self.assertTrue(gl_entries)
-		expected_values = dict(
-			(d[0], d) for d in [["Debtors - _TC", 20.44, 0.0], ["Sales - _TC", 0.0, 20.44]]
-		)
+		expected_values = dict((d[0], d) for d in [
+			['Debtors - _TC', 10.41, 0.0],
+			['Sales - _TC',  0.0, 10.41]
+		])
 		for gle in gl_entries:
 			self.assertEqual(expected_values[gle.account][0], gle.account)
 			self.assertEqual(expected_values[gle.account][1], gle.debit)
 			self.assertEqual(expected_values[gle.account][2], gle.credit)
 
 	def test_payment_entry(self):
-		dunning = create_dunning()
+		dunning = create_second_dunning()
 		dunning.submit()
 		pe = get_payment_entry("Dunning", dunning.name)
 		pe.reference_no = "1"
@@ -80,83 +81,49 @@
 		self.assertEqual(si_doc.outstanding_amount, 0)
 
 
-def create_dunning():
+def create_first_dunning():
 	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")
-	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"
-	dunning.rate_of_interest = dunning_type.rate_of_interest
-	dunning.dunning_fee = dunning_type.dunning_fee
+		posting_date=posting_date, due_date=due_date, qty=1, rate=100)
+	dunning = create_dunning_from_sales_invoice(sales_invoice.name)
 	dunning.save()
+
 	return dunning
 
 
-def create_dunning_with_zero_interest_rate():
+def create_second_dunning():
 	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"
+		posting_date=posting_date, due_date=due_date, qty=1, rate=100)
+	dunning = create_dunning_from_sales_invoice(sales_invoice.name)
+	dunning_type = frappe.get_doc("Dunning Type", "Second Notice")
+
+	dunning.dunning_type = dunning_type.name
 	dunning.rate_of_interest = dunning_type.rate_of_interest
 	dunning.dunning_fee = dunning_type.dunning_fee
 	dunning.save()
+
 	return dunning
 
 
-def create_dunning_type():
+def create_dunning_type(title, fee, interest, is_default):
+	existing = frappe.db.exists("Dunning Type", title)
+	if existing:
+		return frappe.get_doc("Dunning Type", existing)
+
 	dunning_type = frappe.new_doc("Dunning Type")
-	dunning_type.dunning_type = "First Notice"
-	dunning_type.start_day = 10
-	dunning_type.end_day = 20
-	dunning_type.dunning_fee = 20
-	dunning_type.rate_of_interest = 8
+	dunning_type.dunning_type = title
+	dunning_type.is_default = is_default
+	dunning_type.dunning_fee = fee
+	dunning_type.rate_of_interest = interest
 	dunning_type.append(
-		"dunning_letter_text",
-		{
+		"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, including interest and late fees.",
-		},
+			"body_text": "We have still not received payment for our invoice",
+			"closing_text": "We kindly request that you pay the outstanding amount immediately, including interest and late fees."
+		}
 	)
 	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()
+	return dunning_type