test-local-addresses: enable IPv6 on the test interface

If IPv6 is disabled by default, we need to explicitly enable IPv6 on the
interface. Otherwise, adding an IPv6 address or route will fail.

src/test/test-local-addresses.c

@@ -10,6 +10,7 @@
 #include "in-addr-util.h"
 #include "local-addresses.h"
 #include "netlink-util.h"
+#include "sysctl-util.h"
 #include "tests.h"
 
 static bool support_rta_via = false;
@@ -217,6 +218,9 @@ TEST(local_addresses_with_dummy) {
         message = sd_netlink_message_unref(message);
         reply = sd_netlink_message_unref(reply);
 
+        /* Enable IPv6 for the case that it is disabled by default. */
+        ASSERT_OK(sysctl_write_ip_property_boolean(AF_INET6, "test-local-addr", "disable_ipv6", false, /* shadow = */ NULL));
+
         /* Bring the interface up */
         ASSERT_OK(sd_rtnl_message_new_link(rtnl, &message, RTM_SETLINK, ifindex));
         ASSERT_OK(sd_rtnl_message_link_set_flags(message, IFF_UP, IFF_UP));