anchor.diff:  
             with subtest("Wait until we have an ip address on each interface"):
                 client.wait_until_succeeds("ip addr show dev eth1 | grep -q '192.168.1'")
  +
  +          with subtest("ensure MTU is set"):
  +              assert "mtu 1343" in client.succeed("ip link show dev eth1")
   
             with subtest("Test vlan 1"):
                 client.wait_until_succeeds("ping -c 1 192.168.1.1")
  
positive.code:           useDHCP = false;
            interfaces.eth1 = {
              ipv4.addresses = mkOverride 0 [ ];
              useDHCP = true;
            };
            interfaces.eth2.ipv4.addresses = mkOverride 0 [ ];
  
negative.code:             """.format(
                  list, targetList
              )
          with subtest("Test MTU and MAC Address are configured"):
              assert "mtu 1342" in machine.succeed("ip link show dev tap0")
              assert "mtu 1343" in machine.succeed("ip link show dev tun0")
              assert "02:de:ad:be:ef:01" in machine.succeed("ip link show dev tap0")
        '' # network-addresses-* only exist in scripted networking
        + optionalString (!networkd) ''
          with subtest("Test interfaces clean up"):
  