fix: validate coupon pricing rules and validity dates

erpnext/accounts/doctype/coupon_code/coupon_code.js

@@ -5,7 +5,10 @@ frappe.ui.form.on("Coupon Code", {
 	setup: function (frm) {
 		frm.set_query("pricing_rule", function () {
 			return {
-				filters: [["Pricing Rule", "coupon_code_based", "=", "1"]],
+				filters: {
+					coupon_code_based: 1,
+					disable: 0,
+				},
 			};
 		});
 	},

erpnext/accounts/doctype/coupon_code/coupon_code.py

@@ -41,7 +41,23 @@ class CouponCode(Document):
 				self.coupon_code = frappe.generate_hash()[:10].upper()
 
 	def validate(self):
+		self.validate_from_to_dates("valid_from", "valid_upto")
+		self.validate_pricing_rule()
+
 		if self.coupon_type == "Gift Card":
 			self.maximum_use = 1
 			if not self.customer:
 				frappe.throw(_("Please select the customer."))
+
+	def validate_pricing_rule(self):
+		if not self.pricing_rule or self.get("from_external_ecomm_platform"):
+			return
+
+		# Allow existing coupons to be updated after their pricing rule is disabled.
+		if not (
+			self.has_value_changed("pricing_rule") or self.has_value_changed("from_external_ecomm_platform")
+		):
+			return
+
+		if frappe.db.get_value("Pricing Rule", self.pricing_rule, "disable"):
+			frappe.throw(_("Pricing Rule {0} is disabled").format(frappe.bold(self.pricing_rule)))