fix: Add test case for YTD
diff --git a/erpnext/payroll/doctype/employee_tax_exemption_declaration/test_employee_tax_exemption_declaration.py b/erpnext/payroll/doctype/employee_tax_exemption_declaration/test_employee_tax_exemption_declaration.py
index 0609d19..311f352 100644
--- a/erpnext/payroll/doctype/employee_tax_exemption_declaration/test_employee_tax_exemption_declaration.py
+++ b/erpnext/payroll/doctype/employee_tax_exemption_declaration/test_employee_tax_exemption_declaration.py
@@ -86,19 +86,21 @@
 
 		self.assertEqual(declaration.total_exemption_amount, 100000)
 
-def create_payroll_period():
-	if not frappe.db.exists("Payroll Period", "_Test Payroll Period"):
+def create_payroll_period(**args):
+	args = frappe._dict(args)
+	name = args.name or "_Test Payroll Period"
+	if not frappe.db.exists("Payroll Period", name):
 		from datetime import date
 		payroll_period = frappe.get_doc(dict(
 			doctype = 'Payroll Period',
-			name = "_Test Payroll Period",
-			company =  erpnext.get_default_company(),
-			start_date = date(date.today().year, 1, 1),
-			end_date = date(date.today().year, 12, 31)
+			name = name,
+			company =  args.company or erpnext.get_default_company(),
+			start_date = args.start_date or date(date.today().year, 1, 1),
+			end_date = args.end_date or date(date.today().year, 12, 31)
 		)).insert()
 		return payroll_period
 	else:
-		return frappe.get_doc("Payroll Period", "_Test Payroll Period")
+		return frappe.get_doc("Payroll Period", name)
 
 def create_exemption_category():
 	if not frappe.db.exists("Employee Tax Exemption Category", "_Test Category"):
diff --git a/erpnext/payroll/doctype/salary_slip/salary_slip.py b/erpnext/payroll/doctype/salary_slip/salary_slip.py
index 02e5f2d..9f46d50 100644
--- a/erpnext/payroll/doctype/salary_slip/salary_slip.py
+++ b/erpnext/payroll/doctype/salary_slip/salary_slip.py
@@ -18,6 +18,7 @@
 from erpnext.payroll.doctype.employee_benefit_application.employee_benefit_application import get_benefit_component_amount
 from erpnext.payroll.doctype.employee_benefit_claim.employee_benefit_claim import get_benefit_claim_amount, get_last_payroll_period_benefits
 from erpnext.loan_management.doctype.loan_repayment.loan_repayment import calculate_amounts, create_repayment_entry
+from erpnext.accounts.utils import get_fiscal_year
 
 class SalarySlip(TransactionBase):
 	def __init__(self, *args, **kwargs):
@@ -1129,21 +1130,25 @@
 
 	def compute_year_to_date(self):
 		year_to_date = 0
-		payroll_period = frappe.get_list('Payroll Period',
-						fields = ['start_date','end_date','company'],
-						filters= {'start_date' : ['<=', self.start_date],
-									'end_date' : ['>=', self.end_date],
-									'company' : self.company
-						})[0]
-		salary_slips_from_current_payroll_period = frappe.get_list('Salary Slip',
-						fields = ['employee_name', 'start_date', 'end_date', 'net_pay'],
-						filters = {'employee_name' : self.employee_name,
-									'start_date' : ['>=', payroll_period.start_date],
-									'end_date' : ['<', self.start_date]
-						})
+		payroll_period = get_payroll_period(self.start_date, self.end_date, self.company)
 
-		for salary_slip in salary_slips_from_current_payroll_period:
-			year_to_date += salary_slip.net_pay
+		if payroll_period:
+			period_start_date = payroll_period.start_date
+			period_end_date = payroll_period.end_date
+		else:
+			# get dates based on fiscal year if no payroll period exists
+			fiscal_year = get_fiscal_year(date=self.start_date, company=self.company, as_dict=1)
+			period_start_date = fiscal_year.year_start_date
+			period_end_date = fiscal_year.year_end_date
+
+		salary_slip_sum = frappe.get_list('Salary Slip',
+			fields = ['sum(net_pay) as sum'],
+			filters = {'employee_name' : self.employee_name,
+				'start_date' : ['>=', period_start_date],
+				'end_date' : ['<', period_end_date]})
+
+
+		year_to_date = flt(salary_slip_sum[0].sum) if salary_slip_sum else 0.0
 
 		year_to_date += self.net_pay
 		self.year_to_date = year_to_date
@@ -1151,14 +1156,14 @@
 	def compute_month_to_date(self):
 		month_to_date = 0
 		first_day_of_the_month = get_first_day(self.start_date)
-		salary_slips_from_this_month = frappe.get_list('Salary Slip',
-						fields = ['employee_name', 'start_date', 'net_pay'],
-						filters = {'employee_name' : self.employee_name,
-									'start_date' : ['>=', first_day_of_the_month],
-									'end_date' : ['<', self.start_date]
-						})
-		for salary_slip in salary_slips_from_this_month:
-			month_to_date += salary_slip.net_pay
+		salary_slip_sum = frappe.get_list('Salary Slip',
+			fields = ['sum(net_pay) as sum'],
+			filters = {'employee_name' : self.employee_name,
+				'start_date' : ['>=', first_day_of_the_month],
+				'end_date' : ['<', self.start_date]
+			})
+
+		year_to_date = flt(salary_slip_sum[0].sum) if salary_slip_sum else 0.0
 
 		month_to_date += self.net_pay
 		self.month_to_date = month_to_date
diff --git a/erpnext/payroll/doctype/salary_slip/test_salary_slip.py b/erpnext/payroll/doctype/salary_slip/test_salary_slip.py
index 5daf1d4..687d360 100644
--- a/erpnext/payroll/doctype/salary_slip/test_salary_slip.py
+++ b/erpnext/payroll/doctype/salary_slip/test_salary_slip.py
@@ -290,6 +290,35 @@
 		self.assertEqual(salary_slip.gross_pay, 78000)
 		self.assertEqual(salary_slip.base_gross_pay, 78000*70)
 
+	def test_year_to_date_computation(self):
+		from erpnext.payroll.doctype.salary_structure.test_salary_structure import make_salary_structure
+
+		applicant = make_employee("test_ytd@salary.com", company="_Test Company")
+
+		payroll_period = create_payroll_period(name="_Test Payroll Period 1", company="_Test Company",
+			start_date=getdate("2019-04-01"), end_date=getdate("2020-03-31"))
+
+		create_tax_slab(payroll_period, allow_tax_exemption=True, currency="INR", effective_date=getdate("2019-04-01"))
+
+		salary_structure = make_salary_structure("Monthly Salary Structure Test for Salary Slip YTD",
+			"Monthly", employee=applicant, company="_Test Company", currency="INR", payroll_period=payroll_period)
+
+		# clear salary slip for this employee
+		frappe.db.sql("DELETE FROM `tabSalary Slip` where employee_name = 'test_ytd@salary.com'")
+
+		create_salary_slips_for_payroll_period(applicant, salary_structure.name,
+			payroll_period, deduct_random=False)
+
+		salary_slips = frappe.get_all('Salary Slip', fields=['year_to_date'], filters={'employee_name':
+			'test_ytd@salary.com'}, order_by = 'posting_date')
+
+		net_pay = 70026.00
+		month = 1
+		for slip in salary_slips:
+			year_to_date = month * net_pay
+			self.assertEqual(slip.year_to_date, year_to_date)
+			month += 1
+
 	def test_tax_for_payroll_period(self):
 		data = {}
 		# test the impact of tax exemption declaration, tax exemption proof submission
@@ -631,8 +660,13 @@
 	}).submit()
 	return claim_date
 
-def create_tax_slab(payroll_period, effective_date = None, allow_tax_exemption = False, dont_submit = False, currency=erpnext.get_default_currency()):
-	frappe.db.sql("""delete from `tabIncome Tax Slab`""")
+def create_tax_slab(payroll_period, effective_date = None, allow_tax_exemption = False, dont_submit = False, currency=None):
+	# frappe.db.sql("""delete from `tabIncome Tax Slab`""")
+
+	print(payroll_period.name, effective_date)
+
+	if not currency:
+		currency = erpnext.get_default_currency()
 
 	slabs = [
 		{
@@ -652,26 +686,32 @@
 		}
 	]
 
-	income_tax_slab = frappe.new_doc("Income Tax Slab")
-	income_tax_slab.name = "Tax Slab: " + payroll_period.name
-	income_tax_slab.effective_from = effective_date or add_days(payroll_period.start_date, -2)
-	income_tax_slab.currency = currency
+	income_tax_slab_name = frappe.db.get_value("Income Tax Slab", "Tax Slab: " + payroll_period.name)
+	if not income_tax_slab_name:
+		income_tax_slab = frappe.new_doc("Income Tax Slab")
+		income_tax_slab.name = "Tax Slab: " + payroll_period.name
+		income_tax_slab.effective_from = effective_date or add_days(payroll_period.start_date, -2)
+		income_tax_slab.currency = currency
 
-	if allow_tax_exemption:
-		income_tax_slab.allow_tax_exemption = 1
-		income_tax_slab.standard_tax_exemption_amount = 50000
+		if allow_tax_exemption:
+			income_tax_slab.allow_tax_exemption = 1
+			income_tax_slab.standard_tax_exemption_amount = 50000
 
-	for item in slabs:
-		income_tax_slab.append("slabs", item)
+		for item in slabs:
+			income_tax_slab.append("slabs", item)
 
-	income_tax_slab.append("other_taxes_and_charges", {
-		"description": "cess",
-		"percent": 4
-	})
+		income_tax_slab.append("other_taxes_and_charges", {
+			"description": "cess",
+			"percent": 4
+		})
 
-	income_tax_slab.save()
-	if not dont_submit:
-		income_tax_slab.submit()
+		income_tax_slab.save()
+		if not dont_submit:
+			income_tax_slab.submit()
+
+		return income_tax_slab.name
+	else:
+		return income_tax_slab_name
 
 def create_salary_slips_for_payroll_period(employee, salary_structure, payroll_period, deduct_random=True):
 	deducted_dates = []
diff --git a/erpnext/payroll/doctype/salary_structure/test_salary_structure.py b/erpnext/payroll/doctype/salary_structure/test_salary_structure.py
index abb6697..e1c6a00 100644
--- a/erpnext/payroll/doctype/salary_structure/test_salary_structure.py
+++ b/erpnext/payroll/doctype/salary_structure/test_salary_structure.py
@@ -114,7 +114,7 @@
 		self.assertEqual(sal_struct.currency, 'USD')
 
 def make_salary_structure(salary_structure, payroll_frequency, employee=None, dont_submit=False, other_details=None,
-	test_tax=False, company=None, currency=erpnext.get_default_currency()):
+	test_tax=False, company=None, currency=erpnext.get_default_currency(), payroll_period=None):
 	if test_tax:
 		frappe.db.sql("""delete from `tabSalary Structure` where name=%s""",(salary_structure))
 
@@ -141,16 +141,22 @@
 
 	if employee and not frappe.db.get_value("Salary Structure Assignment",
 		{'employee':employee, 'docstatus': 1}) and salary_structure_doc.docstatus==1:
-			create_salary_structure_assignment(employee, salary_structure, company=company, currency=currency)
+			create_salary_structure_assignment(employee, salary_structure, company=company, currency=currency,
+			payroll_period=payroll_period)
 
 	return salary_structure_doc
 
-def create_salary_structure_assignment(employee, salary_structure, from_date=None, company=None, currency=erpnext.get_default_currency()):
+def create_salary_structure_assignment(employee, salary_structure, from_date=None, company=None, currency=erpnext.get_default_currency(),
+	payroll_period=None):
+
 	if frappe.db.exists("Salary Structure Assignment", {"employee": employee}):
 		frappe.db.sql("""delete from `tabSalary Structure Assignment` where employee=%s""",(employee))
 
-	payroll_period = create_payroll_period()
-	create_tax_slab(payroll_period, allow_tax_exemption=True, currency=currency)
+	if not payroll_period:
+		payroll_period = create_payroll_period()
+		income_tax_slab = create_tax_slab(payroll_period, allow_tax_exemption=True, currency=currency)
+	else:
+		income_tax_slab = frappe.db.get_value('Income Tax Slab', "Tax Slab: " + payroll_period.name)
 
 	salary_structure_assignment = frappe.new_doc("Salary Structure Assignment")
 	salary_structure_assignment.employee = employee
@@ -162,7 +168,7 @@
 	salary_structure_assignment.payroll_payable_account = get_payable_account(company)
 	salary_structure_assignment.company = company or erpnext.get_default_company()
 	salary_structure_assignment.save(ignore_permissions=True)
-	salary_structure_assignment.income_tax_slab = "Tax Slab: _Test Payroll Period"
+	salary_structure_assignment.income_tax_slab = income_tax_slab
 	salary_structure_assignment.submit()
 	return salary_structure_assignment