chore: add in a test for failed email notification

Signed-off-by: Akhil Narang <me@akhilnarang.dev>

frappe/email/doctype/email_queue/test_email_queue.py

@@ -1,7 +1,9 @@
 # Copyright (c) 2015, Frappe Technologies and Contributors
 # License: MIT. See LICENSE
+import textwrap
 
 import frappe
+from frappe.email.doctype.email_queue.email_queue import SendMailContext, get_email_retry_limit
 from frappe.tests.utils import FrappeTestCase
 
 
@@ -39,3 +41,40 @@ class TestEmailQueue(FrappeTestCase):
 
 		self.assertTrue(frappe.db.exists("Email Queue", new_record.name))
 		self.assertTrue(frappe.db.exists("Email Queue Recipient", {"parent": new_record.name}))
+
+	def test_failed_email_notification(self):
+		subject = frappe.generate_hash()
+		email_record = frappe.new_doc("Email Queue")
+		email_record.sender = "Test <test@example.com>"
+		email_record.message = textwrap.dedent(
+			f"""\
+		MIME-Version: 1.0
+		Message-Id: {frappe.generate_hash()}
+		X-Original-From: Test <test@example.com>
+		Subject: {subject}
+		From: Test <test@example.com>
+		To: <!--recipient-->
+		Date: {frappe.utils.now_datetime().strftime('%a, %d %b %Y %H:%M:%S %z')}
+		Reply-To: test@example.com
+		X-Frappe-Site: {frappe.local.site}
+		"""
+		)
+		email_record.status = "Error"
+		email_record.retry = get_email_retry_limit()
+		email_record.priority = 1
+		email_record.reference_doctype = "User"
+		email_record.reference_name = "Administrator"
+		email_record.insert()
+
+		# Simulate an exception so that we get a notification
+		try:
+			with SendMailContext(queue_doc=email_record):
+				raise Exception("Test Exception")
+		except Exception:
+			pass
+
+		notification_log = frappe.db.get_value(
+			"Notification Log",
+			{"subject": f"Failed to send email with subject: {subject}"},
+		)
+		self.assertTrue(notification_log)