Skip test case for ipv6 when disable ipv6

spec/ddig/resolver/do53_spec.rb

@@ -109,6 +109,8 @@
 
   context "#lookup: ipv6" do
     before(:each) do
+      skip unless enable_ipv6?
+
       @ip = :ipv6
       @nameservers = ['8.8.8.8', '2001:4860:4860::8888']
 

spec/spec_helper.rb

@@ -2,6 +2,9 @@
 
 require "ddig"
 
+# Load all Rspec support files
+Dir['./spec/support/**/*.rb'].each { |file| require file }
+
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
   config.example_status_persistence_file_path = ".rspec_status"
@@ -12,4 +15,6 @@
   config.expect_with :rspec do |c|
     c.syntax = :expect
   end
+
+  config.include Ddig::Ipv6Helper
 end

spec/support/ipv6_helper.rb

@@ -0,0 +1,20 @@
+module Ddig
+  module Ipv6Helper
+    def enable_ipv6?
+      Socket.ip_address_list.each do |addrinfo|
+        if RUBY_VERSION <= '3.0'
+          # for ipaddr gem <= v1.2.2, Not support zone identifiers in IPv6 addresses
+          addr = IPAddr.new(addrinfo.ip_address.split('%').first)
+        else
+          addr = IPAddr.new(addrinfo.ip_address)
+        end
+
+        if addr.ipv6? && !addr.loopback? && !addr.link_local?
+          return true
+        end
+      end
+
+      return false
+    end
+  end
+end