From 169744261c5c023dff40de0811a826ad4d1fcc05 Mon Sep 17 00:00:00 2001
From: John Shahid <jvshahid@gmail.com>
Date: Fri, 6 Jul 2018 15:38:47 -0400
Subject: [PATCH] Allow reparenting nodes to be a child of an empty document.

Fixes #1773
---
 ext/java/nokogiri/XmlNode.java    |  4 ++++
 test/xml/test_node_reparenting.rb | 11 +++++++++++
 2 files changed, 15 insertions(+)

diff --git a/ext/java/nokogiri/XmlNode.java b/ext/java/nokogiri/XmlNode.java
index 5e126817fc..24439bab9e 100644
--- a/ext/java/nokogiri/XmlNode.java
+++ b/ext/java/nokogiri/XmlNode.java
@@ -1542,6 +1542,10 @@ protected IRubyObject adoptAs(ThreadContext context, AdoptScheme scheme,
          try {
             Document prev = otherNode.getOwnerDocument();
             Document doc = thisNode.getOwnerDocument();
+            if (doc == null && thisNode instanceof Document) {
+              // we are adding the new node to a new empty document
+              doc = (Document) thisNode;
+            }
             clearXpathContext(prev);
             clearXpathContext(doc);
             if (doc != null && doc != otherNode.getOwnerDocument()) {
diff --git a/test/xml/test_node_reparenting.rb b/test/xml/test_node_reparenting.rb
index 02fbe56cc5..2375035c20 100644
--- a/test/xml/test_node_reparenting.rb
+++ b/test/xml/test_node_reparenting.rb
@@ -197,6 +197,17 @@ class TestNodeReparenting < Nokogiri::TestCase
             end
           end
 
+          describe "given the new document is empty" do
+            it "adds the node to the new document" do
+              doc1 = Nokogiri::XML.parse("<value>3</value>")
+              doc2 = Nokogiri::XML::Document.new
+              node = doc1.at_xpath("//value")
+              node.remove
+              doc2.add_child(node)
+              assert_match /<value>3<\/value>/, doc2.to_xml
+            end
+          end
+
           describe "given a parent node with a default namespace" do
             before do
               @doc = Nokogiri::XML(<<-eoxml)