Make sure to add nameservers if using config_info in Resolver

Author: alexdalitz

lib/dnsruby/resolver.rb

@@ -453,6 +453,7 @@ def initialize(*args)
             begin
               if key == :config_info
                 @config.set_config_info(args[0][:config_info])
+                add_config_nameservers
               elsif key == :nameserver
                 set_config_nameserver(args[0][:nameserver])
               elsif key == :nameservers
@@ -509,9 +510,9 @@ def add_config_nameservers # :nodoc: all
       new_resolvers = new_resolvers.select do |resolver|
         !resolver.nil? && !resolver.server.nil?
       end
-      if new_resolvers.empty?
-        raise ArgumentError.new("No valid nameservers found in config")
-      end
+      # if new_resolvers.empty?
+      #   raise ArgumentError.new("No valid nameservers found in config")
+      # end
       @single_res_mutex.synchronize { @single_resolvers.concat(new_resolvers) }
       if @single_resolvers.nil? || @single_resolvers.empty?
         raise ArgumentError.new("No valid nameservers found")

lib/dnsruby/timetest.rb

@@ -477,5 +477,18 @@ def test_threads
 #          Dnsruby::Cache.delete("googlöe.com", "MX")
 
   end
+
+  def test_config_info
+    res = Dnsruby::Resolver.new(
+      config_info: {
+        # contents here doesn't matter; even setting to {} is enough to cause ResolvTimeout
+        apply_domain: false,
+        apply_search_list: false,
+      },
+      query_timeout: 3, # make the timeout faster
+      )
+    res.do_caching = false
+    res.query("a.root-servers.net.", "A")
+  end
 end