From 470a329d9849d108e28f72d00dd130d130cebb01 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Wed, 6 Dec 2023 14:55:03 +0900
Subject: [PATCH] test-network: add test for small MTU for vcan

Prompted by https://github.com/systemd/systemd/issues/30140#issuecomment-1837973580.
---
 test/test-network/conf/25-vcan.netdev       |  1 +
 test/test-network/conf/25-vcan98.netdev     |  4 ++++
 test/test-network/conf/25-vcan98.network    |  6 ++++++
 test/test-network/systemd-networkd-tests.py | 14 ++++++++++++--
 4 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 test/test-network/conf/25-vcan98.netdev
 create mode 100644 test/test-network/conf/25-vcan98.network

diff --git a/test/test-network/conf/25-vcan.netdev b/test/test-network/conf/25-vcan.netdev
index 29bd98e5c9d..2762dd23747 100644
--- a/test/test-network/conf/25-vcan.netdev
+++ b/test/test-network/conf/25-vcan.netdev
@@ -2,3 +2,4 @@
 [NetDev]
 Name=vcan99
 Kind=vcan
+MTUBytes=16
diff --git a/test/test-network/conf/25-vcan98.netdev b/test/test-network/conf/25-vcan98.netdev
new file mode 100644
index 00000000000..5333c82da45
--- /dev/null
+++ b/test/test-network/conf/25-vcan98.netdev
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+[NetDev]
+Name=vcan98
+Kind=vcan
diff --git a/test/test-network/conf/25-vcan98.network b/test/test-network/conf/25-vcan98.network
new file mode 100644
index 00000000000..97f824d2443
--- /dev/null
+++ b/test/test-network/conf/25-vcan98.network
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+[Match]
+Name=vcan98
+
+[Link]
+MTUBytes=16
diff --git a/test/test-network/systemd-networkd-tests.py b/test/test-network/systemd-networkd-tests.py
index 8ffcda37ed9..a9fde69023b 100755
--- a/test/test-network/systemd-networkd-tests.py
+++ b/test/test-network/systemd-networkd-tests.py
@@ -1725,10 +1725,20 @@ class NetworkdNetDevTests(unittest.TestCase, Utilities):
 
     @expectedFailureIfModuleIsNotAvailable('vcan')
     def test_vcan(self):
-        copy_network_unit('25-vcan.netdev', '26-netdev-link-local-addressing-yes.network')
+        copy_network_unit('25-vcan.netdev', '26-netdev-link-local-addressing-yes.network',
+                          '25-vcan98.netdev', '25-vcan98.network')
         start_networkd()
 
-        self.wait_online(['vcan99:carrier'])
+        self.wait_online(['vcan99:carrier', 'vcan98:carrier'])
+
+        # https://github.com/systemd/systemd/issues/30140
+        output = check_output('ip -d link show vcan99')
+        print(output)
+        self.assertIn('mtu 16 ', output)
+
+        output = check_output('ip -d link show vcan98')
+        print(output)
+        self.assertIn('mtu 16 ', output)
 
     @expectedFailureIfModuleIsNotAvailable('vxcan')
     def test_vxcan(self):
-- 
2.47.3