From: Richard Hansen <rhansen@rhansen.org>
Date: Wed, 23 Nov 2022 02:11:16 -0500
Subject: Fix flawed default interface IP address tests

`ddclient::get_default_interface()` doesn't appear to return anything
on the salsa.debian.org CI runners, and subtests can't have 0
checks.

Also, some systems don't have IPv4 or IPv6 addresses on the default
interface.

Forwarded: https://github.com/ddclient/ddclient/pull/698
---
 t/get_ip_from_if.pl | 35 +++++++++++++++++++++--------------
 1 file changed, 21 insertions(+), 14 deletions(-)

diff --git a/t/get_ip_from_if.pl b/t/get_ip_from_if.pl
index 6f08e5d..15c66a1 100644
--- a/t/get_ip_from_if.pl
+++ b/t/get_ip_from_if.pl
@@ -39,23 +39,30 @@ subtest "get_ip_from_interface tests" => sub {
     }
 };
 
-subtest "Get default interface and IP for test system" => sub {
+subtest "Get default interface and IP for test system (IPv4)" => sub {
     my $interface = ddclient::get_default_interface(4);
-    if ($interface) {
-        isnt($interface, "lo", "Check for loopback 'lo'");
-        isnt($interface, "lo0", "Check for loopback 'lo0'");
-        my $ip1 = ddclient::get_ip_from_interface("default", 4);
-        my $ip2 = ddclient::get_ip_from_interface($interface, 4);
-        is($ip1, $ip2, "Check IPv4 from default interface");
+    plan(skip_all => 'no IPv4 interface') if !$interface;
+    isnt($interface, "lo", "Check for loopback 'lo'");
+    isnt($interface, "lo0", "Check for loopback 'lo0'");
+    my $ip1 = ddclient::get_ip_from_interface("default", 4);
+    my $ip2 = ddclient::get_ip_from_interface($interface, 4);
+    is($ip1, $ip2, "Check IPv4 from default interface");
+    SKIP: {
+        skip('default interface does not have an appropriate IPv4 addresses') if !$ip1;
         ok(ddclient::is_ipv4($ip1), "Valid IPv4 from get_ip_from_interface($interface)");
     }
-    $interface = ddclient::get_default_interface(6);
-    if ($interface) {
-        isnt($interface, "lo", "Check for loopback 'lo'");
-        isnt($interface, "lo0", "Check for loopback 'lo0'");
-        my $ip1 = ddclient::get_ip_from_interface("default", 6);
-        my $ip2 = ddclient::get_ip_from_interface($interface, 6);
-        is($ip1, $ip2, "Check IPv6 from default interface");
+};
+
+subtest "Get default interface and IP for test system (IPv6)" => sub {
+    my $interface = ddclient::get_default_interface(6);
+    plan(skip_all => 'no IPv6 interface') if !$interface;
+    isnt($interface, "lo", "Check for loopback 'lo'");
+    isnt($interface, "lo0", "Check for loopback 'lo0'");
+    my $ip1 = ddclient::get_ip_from_interface("default", 6);
+    my $ip2 = ddclient::get_ip_from_interface($interface, 6);
+    is($ip1, $ip2, "Check IPv6 from default interface");
+    SKIP: {
+        skip('default interface does not have an appropriate IPv6 addresses') if !$ip1;
         ok(ddclient::is_ipv6($ip1), "Valid IPv6 from get_ip_from_interface($interface)");
     }
 };