test: Update test cases for currency change validation
diff --git a/erpnext/accounts/doctype/period_closing_voucher/test_period_closing_voucher.py b/erpnext/accounts/doctype/period_closing_voucher/test_period_closing_voucher.py
index f17a5c5..18f9549 100644
--- a/erpnext/accounts/doctype/period_closing_voucher/test_period_closing_voucher.py
+++ b/erpnext/accounts/doctype/period_closing_voucher/test_period_closing_voucher.py
@@ -81,7 +81,8 @@
 			income_account="Sales - TPC",
 			expense_account="Cost of Goods Sold - TPC",
 			rate=400,
-			debit_to="Debtors - TPC"
+			debit_to="Debtors - TPC",
+			currency="USD"
 		)
 		create_sales_invoice(
 			company=company,
@@ -89,7 +90,8 @@
 			income_account="Sales - TPC",
 			expense_account="Cost of Goods Sold - TPC",
 			rate=200,
-			debit_to="Debtors - TPC"
+			debit_to="Debtors - TPC",
+			currency="USD"
 		)
 
 		pcv = frappe.get_doc({
diff --git a/erpnext/controllers/accounts_controller.py b/erpnext/controllers/accounts_controller.py
index a801245..654e0eb 100644
--- a/erpnext/controllers/accounts_controller.py
+++ b/erpnext/controllers/accounts_controller.py
@@ -1113,6 +1113,9 @@
 		if self.doctype not in ('Sales Invoice', 'Purchase Invoice'):
 			return
 
+		if self.is_opening == 'Yes':
+			return
+
 		party_type, party = self.get_party()
 		party_gle_currency = get_party_gle_currency(party_type, party, self.company)
 		party_account = self.get('debit_to') if self.doctype == 'Sales Invoice' else self.get('credit_to')
diff --git a/erpnext/healthcare/doctype/patient_appointment/patient_appointment.py b/erpnext/healthcare/doctype/patient_appointment/patient_appointment.py
index cdd4ad3..12f2fe1 100755
--- a/erpnext/healthcare/doctype/patient_appointment/patient_appointment.py
+++ b/erpnext/healthcare/doctype/patient_appointment/patient_appointment.py
@@ -14,6 +14,7 @@
 from erpnext.hr.doctype.employee.employee import is_holiday
 from erpnext.healthcare.doctype.healthcare_settings.healthcare_settings import get_receivable_account, get_income_account
 from erpnext.healthcare.utils import check_fee_validity, get_service_item_and_practitioner_charge, manage_fee_validity
+from erpnext import get_company_currency
 
 class PatientAppointment(Document):
 	def validate(self):
@@ -164,6 +165,8 @@
 	sales_invoice = frappe.new_doc('Sales Invoice')
 	sales_invoice.patient = appointment_doc.patient
 	sales_invoice.customer = frappe.get_value('Patient', appointment_doc.patient, 'customer')
+	sales_invoice.currency = frappe.get_value('Customer', sales_invoice.customer, 'default_currency') \
+		or get_company_currency(appointment_doc.currency)
 	sales_invoice.appointment = appointment_doc.name
 	sales_invoice.due_date = getdate()
 	sales_invoice.company = appointment_doc.company
diff --git a/erpnext/healthcare/doctype/therapy_plan/therapy_plan.py b/erpnext/healthcare/doctype/therapy_plan/therapy_plan.py
index e209660..c29f6a0 100644
--- a/erpnext/healthcare/doctype/therapy_plan/therapy_plan.py
+++ b/erpnext/healthcare/doctype/therapy_plan/therapy_plan.py
@@ -6,6 +6,7 @@
 import frappe
 from frappe.model.document import Document
 from frappe.utils import flt, today
+from erpnext import get_company_currency
 
 class TherapyPlan(Document):
 	def validate(self):
@@ -73,6 +74,8 @@
 	si.company = company
 	si.patient = patient
 	si.customer = frappe.db.get_value('Patient', patient, 'customer')
+	si.currency = frappe.get_value('Customer', si.customer, 'default_currency') \
+		or get_company_currency(si.company)
 
 	item = frappe.db.get_value('Therapy Plan Template', therapy_plan_template, 'linked_item')
 	price_list, price_list_currency = frappe.db.get_values('Price List', {'selling': 1}, ['name', 'currency'])[0]
diff --git a/erpnext/non_profit/doctype/membership/membership.py b/erpnext/non_profit/doctype/membership/membership.py
index b584116..88284f8 100644
--- a/erpnext/non_profit/doctype/membership/membership.py
+++ b/erpnext/non_profit/doctype/membership/membership.py
@@ -14,6 +14,7 @@
 from erpnext.non_profit.doctype.member.member import create_member
 from frappe import _
 import erpnext
+from erpnext import get_company_currency
 
 class Membership(Document):
 	def validate(self):
@@ -176,7 +177,7 @@
 		"doctype": "Sales Invoice",
 		"customer": member.customer,
 		"debit_to": settings.membership_debit_account,
-		"currency": membership.currency,
+		"currency": membership.currency or get_company_currency(settings.company),
 		"company": settings.company,
 		"is_pos": 0,
 		"items": [
diff --git a/erpnext/non_profit/doctype/membership/test_membership.py b/erpnext/non_profit/doctype/membership/test_membership.py
index 5ad2088..5c876df 100644
--- a/erpnext/non_profit/doctype/membership/test_membership.py
+++ b/erpnext/non_profit/doctype/membership/test_membership.py
@@ -80,7 +80,7 @@
 		"member": member,
 		"membership_status": "Current",
 		"membership_type": "_rzpy_test_milythm",
-		"currency": "INR",
+		"currency": "USD",
 		"paid": 1,
 		"from_date": nowdate(),
 		"amount": 100