####
my $dom = XML::LibXML::Document->new('1.0', 'utf-8');
my $xml1 = XML::LibXML->load_xml(location => 'file1.xml');
my $xml2 = XML::LibXML->load_xml(location => 'file2.xml');
my $root = $dom->createElement('testsuites');
$dom->setDocumentElement($root);
my $testsuite1 = $xml1->findnodes('//testsuite');
my $testsuite2 = $xml2->findnodes('//testsuite');
my $child = $dom->createElement($testsuite1); # <-- fails
$root->appendChild($child);
open XML, ">result.xml";
print XML $dom->toString();
close XML;