fixed test cases and the logic for pro rata calculation
diff --git a/erpnext/assets/doctype/asset/asset.py b/erpnext/assets/doctype/asset/asset.py
index 6475d0c..45d2ec2 100644
--- a/erpnext/assets/doctype/asset/asset.py
+++ b/erpnext/assets/doctype/asset/asset.py
@@ -6,7 +6,7 @@
 import frappe, erpnext, math, json
 from frappe import _
 from six import string_types
-from frappe.utils import flt, add_months, cint, nowdate, getdate, today, date_diff
+from frappe.utils import flt, add_months, cint, nowdate, getdate, today, date_diff, add_days
 from frappe.model.document import Document
 from erpnext.assets.doctype.asset_category.asset_category import get_asset_category_account
 from erpnext.assets.doctype.asset.depreciation \
@@ -105,73 +105,84 @@
 				d.precision("rate_of_depreciation"))
 
 	def make_depreciation_schedule(self):
-		depreciation_method = [d.depreciation_method for d in self.finance_books]
-
-		if 'Manual' not in depreciation_method:
+		if 'Manual' not in [d.depreciation_method for d in self.finance_books]:
 			self.schedules = []
 
-		if not self.get("schedules") and self.available_for_use_date:
-			for d in self.get('finance_books'):
-				self.validate_asset_finance_books(d)
+		if self.get("schedules") or not self.available_for_use_date:
+			return
 
-				value_after_depreciation = (flt(self.gross_purchase_amount) -
-					flt(self.opening_accumulated_depreciation))
+		for d in self.get('finance_books'):
+			self.validate_asset_finance_books(d)
 
-				d.value_after_depreciation = value_after_depreciation
+			value_after_depreciation = (flt(self.gross_purchase_amount) -
+				flt(self.opening_accumulated_depreciation))
 
-				no_of_depreciations = cint(d.total_number_of_depreciations - 1) - cint(self.number_of_depreciations_booked)
-				end_date = add_months(d.depreciation_start_date,
-					no_of_depreciations * cint(d.frequency_of_depreciation))
+			d.value_after_depreciation = value_after_depreciation
 
-				if d.depreciation_method in ("Straight Line", "Manual"):
-					total_days = date_diff(end_date, self.available_for_use_date)
-					rate_per_day = (value_after_depreciation - d.get("expected_value_after_useful_life")) / total_days
+			number_of_pending_depreciations = cint(d.total_number_of_depreciations) - \
+				cint(self.number_of_depreciations_booked)
 
-				number_of_pending_depreciations = cint(d.total_number_of_depreciations) - \
-					cint(self.number_of_depreciations_booked)
+			has_pro_rata = self.check_is_pro_rata(d)
 
-				from_date = self.available_for_use_date
-				if number_of_pending_depreciations:
-					period_start_date = add_months(d.depreciation_start_date,
-						cint(d.frequency_of_depreciation) * -1)
+			if has_pro_rata:
+				number_of_pending_depreciations += 1
 
-					for n in range(number_of_pending_depreciations):
-						schedule_date = add_months(d.depreciation_start_date,
-							n * cint(d.frequency_of_depreciation))
+			skip_row = False
+			for n in range(number_of_pending_depreciations):
+				# If depreciation is already completed (for double declining balance)
+				if skip_row: continue
 
-						days = date_diff(schedule_date, from_date)
+				depreciation_amount = self.get_depreciation_amount(value_after_depreciation,
+					d.total_number_of_depreciations, d)
 
-						if n == 0: days += 1
+				if not has_pro_rata or n < cint(number_of_pending_depreciations) - 1:
+					schedule_date = add_months(d.depreciation_start_date,
+						n * cint(d.frequency_of_depreciation))
 
-						if d.depreciation_method in ("Straight Line", "Manual"):
-							depreciation_amount = days * rate_per_day
-						else:
-							total_days = date_diff(schedule_date, period_start_date)
-							period_start_date = schedule_date
-							depreciation_amount = self.get_depreciation_amount(value_after_depreciation,
-								d.total_number_of_depreciations, d)
+				# For first row
+				if has_pro_rata and n==0:
+					depreciation_amount, days = get_pro_rata_amt(d, depreciation_amount,
+						self.available_for_use_date, d.depreciation_start_date)
+				# For last row
+				elif has_pro_rata and n == cint(number_of_pending_depreciations) - 1:
+					to_date = add_months(self.available_for_use_date,
+						n * cint(d.frequency_of_depreciation))
 
-							depreciation_amount = flt((depreciation_amount * days) / total_days,
-								self.precision("gross_purchase_amount"))
+					depreciation_amount, days = get_pro_rata_amt(d,
+						depreciation_amount, schedule_date, to_date)
 
-						from_date = schedule_date
+					schedule_date = add_days(schedule_date, days)
 
-						if depreciation_amount:
-							value_after_depreciation -= flt(depreciation_amount,
-								self.precision("gross_purchase_amount"))
+				if not depreciation_amount: continue
+				value_after_depreciation -= flt(depreciation_amount,
+					self.precision("gross_purchase_amount"))
 
-							if (n == cint(number_of_pending_depreciations) - 1 and
-								d.expected_value_after_useful_life and
-								value_after_depreciation > d.expected_value_after_useful_life):
-								depreciation_amount += (value_after_depreciation - d.expected_value_after_useful_life)
+				# Adjust depreciation amount in the last period based on the expected value after useful life
+				if d.expected_value_after_useful_life and ((n == cint(number_of_pending_depreciations) - 1
+					and value_after_depreciation != d.expected_value_after_useful_life)
+					or value_after_depreciation < d.expected_value_after_useful_life):
+					depreciation_amount += (value_after_depreciation - d.expected_value_after_useful_life)
+					skip_row = True
 
-							self.append("schedules", {
-								"schedule_date": schedule_date,
-								"depreciation_amount": depreciation_amount,
-								"depreciation_method": d.depreciation_method,
-								"finance_book": d.finance_book,
-								"finance_book_id": d.idx
-							})
+				if depreciation_amount > 0:
+					self.append("schedules", {
+						"schedule_date": schedule_date,
+						"depreciation_amount": depreciation_amount,
+						"depreciation_method": d.depreciation_method,
+						"finance_book": d.finance_book,
+						"finance_book_id": d.idx
+					})
+
+	def check_is_pro_rata(self, row):
+		has_pro_rata = False
+
+		days = date_diff(row.depreciation_start_date, self.available_for_use_date) + 1
+		total_days = get_total_days(row.depreciation_start_date, row.frequency_of_depreciation)
+
+		if days < total_days:
+			has_pro_rata = True
+
+		return has_pro_rata
 
 	def validate_asset_finance_books(self, row):
 		if flt(row.expected_value_after_useful_life) >= flt(self.gross_purchase_amount):
@@ -242,22 +253,13 @@
 
 	def get_depreciation_amount(self, depreciable_value, total_number_of_depreciations, row):
 		precision = self.precision("gross_purchase_amount")
-		depreciation_amount = flt(depreciable_value * (flt(row.rate_of_depreciation) / 100), precision)
-
-		return depreciation_amount
-
-	def get_depreciation_amount_prorata_temporis(self, depreciable_value, row, start_date=None, end_date=None):
-		if start_date and end_date:
-			prorata_temporis =  min(abs(flt(date_diff(str(end_date), str(start_date)))) / flt(frappe.db.get_value("Asset Settings", None, "number_of_days_in_fiscal_year")), 1)
-		else:
-			prorata_temporis = 1
 
 		if row.depreciation_method in ("Straight Line", "Manual"):
 			depreciation_amount = (flt(row.value_after_depreciation) -
 				flt(row.expected_value_after_useful_life)) / (cint(row.total_number_of_depreciations) -
-				cint(self.number_of_depreciations_booked)) * prorata_temporis
+				cint(self.number_of_depreciations_booked))
 		else:
-			depreciation_amount = self.get_depreciation_amount(depreciable_value, row.total_number_of_depreciations, row)
+			depreciation_amount = flt(depreciable_value * (flt(row.rate_of_depreciation) / 100), precision)
 
 		return depreciation_amount
 
@@ -387,15 +389,7 @@
 		if isinstance(args, string_types):
 			args = json.loads(args)
 
-		number_of_depreciations_booked = 0
-		if self.is_existing_asset:
-			number_of_depreciations_booked = self.number_of_depreciations_booked
-
 		float_precision = cint(frappe.db.get_default("float_precision")) or 2
-		tot_no_of_depreciation = flt(args.get("total_number_of_depreciations")) - flt(number_of_depreciations_booked)
-
-		if args.get("depreciation_method") in ["Straight Line", "Manual"]:
-			return 1.0 / tot_no_of_depreciation
 
 		if args.get("depreciation_method") == 'Double Declining Balance':
 			return 200.0 / args.get("total_number_of_depreciations")
@@ -575,3 +569,15 @@
 
 def is_cwip_accounting_disabled():
 	return cint(frappe.db.get_single_value("Asset Settings", "disable_cwip_accounting"))
+
+def get_pro_rata_amt(row, depreciation_amount, from_date, to_date):
+	days = date_diff(to_date, from_date)
+	total_days = get_total_days(to_date, row.frequency_of_depreciation)
+
+	return (depreciation_amount * flt(days)) / flt(total_days), days
+
+def get_total_days(date, frequency):
+	period_start_date = add_months(date,
+		cint(frequency) * -1)
+
+	return date_diff(date, period_start_date)
\ No newline at end of file
diff --git a/erpnext/assets/doctype/asset/test_asset.py b/erpnext/assets/doctype/asset/test_asset.py
index fceccfb..481ee7d 100644
--- a/erpnext/assets/doctype/asset/test_asset.py
+++ b/erpnext/assets/doctype/asset/test_asset.py
@@ -88,23 +88,23 @@
 		asset_name = frappe.db.get_value("Asset", {"purchase_receipt": pr.name}, 'name')
 		asset = frappe.get_doc('Asset', asset_name)
 		asset.calculate_depreciation = 1
-		asset.available_for_use_date = '2020-06-06'
-		asset.purchase_date = '2020-06-06'
+		asset.available_for_use_date = '2030-01-01'
+		asset.purchase_date = '2030-01-01'
 
 		asset.append("finance_books", {
 			"expected_value_after_useful_life": 10000,
-			"next_depreciation_date": "2020-12-31",
 			"depreciation_method": "Straight Line",
 			"total_number_of_depreciations": 3,
-			"frequency_of_depreciation": 10,
-			"depreciation_start_date": "2020-06-06"
+			"frequency_of_depreciation": 12,
+			"depreciation_start_date": "2030-12-31"
 		})
 		asset.save()
+
 		self.assertEqual(asset.status, "Draft")
 		expected_schedules = [
-			["2020-06-06", 147.54, 147.54],
-			["2021-04-06", 44852.46, 45000.0],
-			["2022-02-06", 45000.0, 90000.00]
+			["2030-12-31", 30000.00, 30000.00],
+			["2031-12-31", 30000.00, 60000.00],
+			["2032-12-31", 30000.00, 90000.00]
 		]
 
 		schedules = [[cstr(d.schedule_date), d.depreciation_amount, d.accumulated_depreciation_amount]
@@ -118,20 +118,21 @@
 		asset.calculate_depreciation = 1
 		asset.number_of_depreciations_booked = 1
 		asset.opening_accumulated_depreciation = 40000
+		asset.available_for_use_date = "2030-06-06"
 		asset.append("finance_books", {
 			"expected_value_after_useful_life": 10000,
-			"next_depreciation_date": "2020-12-31",
 			"depreciation_method": "Straight Line",
 			"total_number_of_depreciations": 3,
-			"frequency_of_depreciation": 10,
-			"depreciation_start_date": "2020-06-06"
+			"frequency_of_depreciation": 12,
+			"depreciation_start_date": "2030-12-31"
 		})
 		asset.insert()
 		self.assertEqual(asset.status, "Draft")
 		asset.save()
 		expected_schedules = [
-			["2020-06-06", 164.47, 40164.47],
-			["2021-04-06", 49835.53, 90000.00]
+			["2030-12-31", 14246.58, 54246.58],
+			["2031-12-31", 25000.00, 79246.58],
+			["2032-06-06", 10753.42, 90000.00]
 		]
 		schedules = [[cstr(d.schedule_date), flt(d.depreciation_amount, 2), d.accumulated_depreciation_amount]
 			for d in asset.get("schedules")]
@@ -145,24 +146,23 @@
 		asset_name = frappe.db.get_value("Asset", {"purchase_receipt": pr.name}, 'name')
 		asset = frappe.get_doc('Asset', asset_name)
 		asset.calculate_depreciation = 1
-		asset.available_for_use_date = '2020-06-06'
-		asset.purchase_date = '2020-06-06'
+		asset.available_for_use_date = '2030-01-01'
+		asset.purchase_date = '2030-01-01'
 		asset.append("finance_books", {
 			"expected_value_after_useful_life": 10000,
-			"next_depreciation_date": "2020-12-31",
 			"depreciation_method": "Double Declining Balance",
 			"total_number_of_depreciations": 3,
-			"frequency_of_depreciation": 10,
-			"depreciation_start_date": "2020-06-06"
+			"frequency_of_depreciation": 12,
+			"depreciation_start_date": '2030-12-31'
 		})
 		asset.insert()
 		self.assertEqual(asset.status, "Draft")
 		asset.save()
 
 		expected_schedules = [
-			["2020-06-06", 66666.67, 66666.67],
-			["2021-04-06", 22222.22, 88888.89],
-			["2022-02-06", 1111.11, 90000.0]
+			['2030-12-31', 66667.00, 66667.00],
+			['2031-12-31', 22222.11, 88889.11],
+			['2032-12-31', 1110.89, 90000.0]
 		]
 
 		schedules = [[cstr(d.schedule_date), d.depreciation_amount, d.accumulated_depreciation_amount]
@@ -177,23 +177,21 @@
 		asset.is_existing_asset = 1
 		asset.number_of_depreciations_booked = 1
 		asset.opening_accumulated_depreciation = 50000
+		asset.available_for_use_date = '2030-01-01'
+		asset.purchase_date = '2029-11-30'
 		asset.append("finance_books", {
 			"expected_value_after_useful_life": 10000,
-			"next_depreciation_date": "2020-12-31",
 			"depreciation_method": "Double Declining Balance",
 			"total_number_of_depreciations": 3,
-			"frequency_of_depreciation": 10,
-			"depreciation_start_date": "2020-06-06"
+			"frequency_of_depreciation": 12,
+			"depreciation_start_date": "2030-12-31"
 		})
 		asset.insert()
 		self.assertEqual(asset.status, "Draft")
-		asset.save()
-
-		asset.save()
 
 		expected_schedules = [
-			["2020-06-06", 33333.33, 83333.33],
-			["2021-04-06", 6666.67, 90000.0]
+			["2030-12-31", 33333.50, 83333.50],
+			["2031-12-31", 6666.50, 90000.0]
 		]
 
 		schedules = [[cstr(d.schedule_date), d.depreciation_amount, d.accumulated_depreciation_amount]
@@ -209,25 +207,25 @@
 		asset_name = frappe.db.get_value("Asset", {"purchase_receipt": pr.name}, 'name')
 		asset = frappe.get_doc('Asset', asset_name)
 		asset.calculate_depreciation = 1
-		asset.purchase_date = '2020-01-30'
+		asset.purchase_date = '2030-01-30'
 		asset.is_existing_asset = 0
-		asset.available_for_use_date = "2020-01-30"
+		asset.available_for_use_date = "2030-01-30"
 		asset.append("finance_books", {
 			"expected_value_after_useful_life": 10000,
 			"depreciation_method": "Straight Line",
 			"total_number_of_depreciations": 3,
-			"frequency_of_depreciation": 10,
-			"depreciation_start_date": "2020-12-31"
+			"frequency_of_depreciation": 12,
+			"depreciation_start_date": "2030-12-31"
 		})
 
 		asset.insert()
 		asset.save()
 
 		expected_schedules = [
-			["2020-12-31", 28000.0, 28000.0],
-			["2021-12-31", 30000.0, 58000.0],
-			["2022-12-31", 30000.0, 88000.0],
-			["2023-01-30", 2000.0, 90000.0]
+			["2030-12-31", 27534.25, 27534.25],
+			["2031-12-31", 30000.0, 57534.25],
+			["2032-12-31", 30000.0, 87534.25],
+			["2033-01-30", 2465.75, 90000.0]
 		]
 
 		schedules = [[cstr(d.schedule_date), flt(d.depreciation_amount, 2), flt(d.accumulated_depreciation_amount, 2)]
@@ -266,8 +264,8 @@
 		self.assertEqual(asset.get("schedules")[0].journal_entry[:4], "DEPR")
 
 		expected_gle = (
-			("_Test Accumulated Depreciations - _TC", 0.0, 32129.24),
-			("_Test Depreciations - _TC", 32129.24, 0.0)
+			("_Test Accumulated Depreciations - _TC", 0.0, 30000.0),
+			("_Test Depreciations - _TC", 30000.0, 0.0)
 		)
 
 		gle = frappe.db.sql("""select account, debit, credit from `tabGL Entry`
@@ -277,15 +275,15 @@
 		self.assertEqual(gle, expected_gle)
 		self.assertEqual(asset.get("value_after_depreciation"), 0)
 
-	def test_depreciation_entry_for_wdv(self):
+	def test_depreciation_entry_for_wdv_without_pro_rata(self):
 		pr = make_purchase_receipt(item_code="Macbook Pro",
 			qty=1, rate=8000.0, location="Test Location")
 
 		asset_name = frappe.db.get_value("Asset", {"purchase_receipt": pr.name}, 'name')
 		asset = frappe.get_doc('Asset', asset_name)
 		asset.calculate_depreciation = 1
-		asset.available_for_use_date = '2030-06-06'
-		asset.purchase_date = '2030-06-06'
+		asset.available_for_use_date = '2030-01-01'
+		asset.purchase_date = '2030-01-01'
 		asset.append("finance_books", {
 			"expected_value_after_useful_life": 1000,
 			"depreciation_method": "Written Down Value",
@@ -298,9 +296,41 @@
 		self.assertEqual(asset.finance_books[0].rate_of_depreciation, 50.0)
 
 		expected_schedules = [
-			["2030-12-31", 4000.0, 4000.0],
-			["2031-12-31", 2000.0, 6000.0],
-			["2032-12-31", 1000.0, 7000.0],
+			["2030-12-31", 4000.00, 4000.00],
+			["2031-12-31", 2000.00, 6000.00],
+			["2032-12-31", 1000.00, 7000.0],
+		]
+
+		schedules = [[cstr(d.schedule_date), flt(d.depreciation_amount, 2), flt(d.accumulated_depreciation_amount, 2)]
+			for d in asset.get("schedules")]
+
+		self.assertEqual(schedules, expected_schedules)
+
+	def test_pro_rata_depreciation_entry_for_wdv(self):
+		pr = make_purchase_receipt(item_code="Macbook Pro",
+			qty=1, rate=8000.0, location="Test Location")
+
+		asset_name = frappe.db.get_value("Asset", {"purchase_receipt": pr.name}, 'name')
+		asset = frappe.get_doc('Asset', asset_name)
+		asset.calculate_depreciation = 1
+		asset.available_for_use_date = '2030-06-06'
+		asset.purchase_date = '2030-01-01'
+		asset.append("finance_books", {
+			"expected_value_after_useful_life": 1000,
+			"depreciation_method": "Written Down Value",
+			"total_number_of_depreciations": 3,
+			"frequency_of_depreciation": 12,
+			"depreciation_start_date": "2030-12-31"
+		})
+		asset.save(ignore_permissions=True)
+
+		self.assertEqual(asset.finance_books[0].rate_of_depreciation, 50.0)
+
+		expected_schedules = [
+			["2030-12-31", 2279.45, 2279.45],
+			["2031-12-31", 2860.28, 5139.73],
+			["2032-12-31", 1430.14, 6569.87],
+			["2033-06-06", 430.13, 7000.0],
 		]
 
 		schedules = [[cstr(d.schedule_date), flt(d.depreciation_amount, 2), flt(d.accumulated_depreciation_amount, 2)]
@@ -346,18 +376,19 @@
 		asset_name = frappe.db.get_value("Asset", {"purchase_receipt": pr.name}, 'name')
 		asset = frappe.get_doc('Asset', asset_name)
 		asset.calculate_depreciation = 1
-		asset.available_for_use_date = '2020-06-06'
-		asset.purchase_date = '2020-06-06'
+		asset.available_for_use_date = nowdate()
+		asset.purchase_date = nowdate()
 		asset.append("finance_books", {
 			"expected_value_after_useful_life": 10000,
 			"depreciation_method": "Straight Line",
 			"total_number_of_depreciations": 3,
 			"frequency_of_depreciation": 10,
-			"depreciation_start_date": "2020-06-06"
+			"depreciation_start_date": nowdate()
 		})
 		asset.insert()
 		asset.submit()
-		post_depreciation_entries(date="2021-01-01")
+
+		post_depreciation_entries(date=add_months(nowdate(), 10))
 
 		scrap_asset(asset.name)
 
@@ -366,9 +397,9 @@
 		self.assertTrue(asset.journal_entry_for_scrap)
 
 		expected_gle = (
-			("_Test Accumulated Depreciations - _TC", 147.54, 0.0),
+			("_Test Accumulated Depreciations - _TC", 30000.0, 0.0),
 			("_Test Fixed Asset - _TC", 0.0, 100000.0),
-			("_Test Gain/Loss on Asset Disposal - _TC", 99852.46, 0.0)
+			("_Test Gain/Loss on Asset Disposal - _TC", 70000.0, 0.0)
 		)
 
 		gle = frappe.db.sql("""select account, debit, credit from `tabGL Entry`
@@ -412,9 +443,9 @@
 		self.assertEqual(frappe.db.get_value("Asset", asset.name, "status"), "Sold")
 
 		expected_gle = (
-			("_Test Accumulated Depreciations - _TC", 23051.47, 0.0),
+			("_Test Accumulated Depreciations - _TC", 20392.16, 0.0),
 			("_Test Fixed Asset - _TC", 0.0, 100000.0),
-			("_Test Gain/Loss on Asset Disposal - _TC", 51948.53, 0.0),
+			("_Test Gain/Loss on Asset Disposal - _TC", 54607.84, 0.0),
 			("Debtors - _TC", 25000.0, 0.0)
 		)