feat(tests): test payment_notification

diff --git a/tests/device_tests/misc/test_msg_paymentnotification.py b/tests/device_tests/misc/test_msg_paymentnotification.py
new file mode 100644
index 000000000..ae6ed5aff
--- /dev/null
+++ b/tests/device_tests/misc/test_msg_paymentnotification.py
@@ -0,0 +1,52 @@
+# This file is part of the Trezor project.
+#
+# Copyright (C) 2012-2025 SatoshiLabs and contributors
+#
+# This library is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License version 3
+# as published by the Free Software Foundation.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the License along with this library.
+# If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
+
+import pytest
+
+from trezorlib import btc, misc
+from trezorlib.debuglink import SessionDebugWrapper as Session
+from trezorlib.tools import parse_path
+
+
+@pytest.mark.experimental
+@pytest.mark.models("core")
+def test_paymentnotification(session: Session):
+    from ..payment_req import CoinPurchaseMemo, TextMemo, make_payment_request
+
+    purchase_memo = CoinPurchaseMemo(
+        amount="0.0636 BTC",
+        coin_name="Bitcoin",
+        slip44=0,
+        address_n=parse_path("m/44h/0h/0h/0/0"),
+    )
+    purchase_memo.address_resp = btc.get_authenticated_address(
+        session, purchase_memo.coin_name, purchase_memo.address_n
+    )
+
+    text_memo = TextMemo("We will deduct 1234.56 USD from your account")
+
+    nonce = misc.get_nonce(session)
+    payment_request = make_payment_request(
+        session,
+        recipient_name="trezor.io",
+        slip44=0,
+        outputs=None,
+        memos=[purchase_memo, text_memo],
+        nonce=nonce,
+        amount_size_bytes=8,
+    )
+
+    misc.payment_notification(session, payment_request)
diff --git a/tests/device_tests/payment_req.py b/tests/device_tests/payment_req.py
index bc523bd13..08f49043e 100644
--- a/tests/device_tests/payment_req.py
+++ b/tests/device_tests/payment_req.py
@@ -116,7 +116,7 @@ def make_payment_request(
 
     change_address = iter(change_addresses or [])
     h_outputs = sha256()
-    for amount, address in outputs:
+    for amount, address in outputs or []:
         h_outputs.update(amount.to_bytes(amount_size_bytes, "little"))
         if not address:
             address = next(change_address)
@@ -125,11 +125,17 @@ def make_payment_request(
 
     h_pr.update(h_outputs.digest())
 
-    amount = sum(amount for amount, address in outputs if address)
+    amount = (
+        sum(amount for amount, address in outputs if address)
+        if outputs is not None
+        else None
+    )
 
     return messages.PaymentRequest(
         recipient_name=recipient_name,
-        amount=amount.to_bytes(amount_size_bytes, "little"),
+        amount=(
+            amount.to_bytes(amount_size_bytes, "little") if amount is not None else None
+        ),
         memos=msg_memos,
         nonce=nonce,
         signature=payment_req_signer.sign_digest_deterministic(h_pr.digest()),