refactor(test): supply default currency for subscription plans
diff --git a/erpnext/accounts/doctype/subscription/test_subscription.py b/erpnext/accounts/doctype/subscription/test_subscription.py
index 785fd04..37326fd 100644
--- a/erpnext/accounts/doctype/subscription/test_subscription.py
+++ b/erpnext/accounts/doctype/subscription/test_subscription.py
@@ -463,7 +463,7 @@
 		subscription = create_subscription(
 			start_date="2018-01-01",
 			generate_invoice_at="Beginning of the current subscription period",
-			plans=[{"plan": "_Test Plan Multicurrency", "qty": 1}],
+			plans=[{"plan": "_Test Plan Multicurrency", "qty": 1, "currency": "USD"}],
 			party="_Test Subscription Customer",
 		)
 
@@ -528,13 +528,21 @@
 
 
 def make_plans():
-	create_plan(plan_name="_Test Plan Name", cost=900)
-	create_plan(plan_name="_Test Plan Name 2", cost=1999)
+	create_plan(plan_name="_Test Plan Name", cost=900, currency="INR")
+	create_plan(plan_name="_Test Plan Name 2", cost=1999, currency="INR")
 	create_plan(
-		plan_name="_Test Plan Name 3", cost=1999, billing_interval="Day", billing_interval_count=14
+		plan_name="_Test Plan Name 3",
+		cost=1999,
+		billing_interval="Day",
+		billing_interval_count=14,
+		currency="INR",
 	)
 	create_plan(
-		plan_name="_Test Plan Name 4", cost=20000, billing_interval="Month", billing_interval_count=3
+		plan_name="_Test Plan Name 4",
+		cost=20000,
+		billing_interval="Month",
+		billing_interval_count=3,
+		currency="INR",
 	)
 	create_plan(
 		plan_name="_Test Plan Multicurrency", cost=50, billing_interval="Month", currency="USD"