Изменён способ добавления аттрибутов на правильный

.jshintrc

@@ -1,14 +0,0 @@
-{
-  "esversion":6,
-  "curly": true,
-  "eqeqeq": true,
-  "immed": true,
-  "latedef": true,
-  "newcap": true,
-  "noarg": true,
-  "sub": true,
-  "undef": true,
-  "boss": true,
-  "eqnull": true,
-  "node": true
-}

lib/index.js

@@ -48,13 +48,20 @@ function generateXML(data) {
             ifTruePush(item.related, item_values, {
                 'yandex:related': item.related.map(
                     function (related) {
-                        return '<link url="' + related.link + '" img="' + related.image_url + '">' + related.text + '</link>';
+                        return {
+                            link: [{
+                                _attr: {
+                                    'url': related.link,
+                                    'img': related.image_url
+                                }
+                            }, related.text]
+                        };
                     }
-                ).join('')
+                )
             });
         }
-        channel.push({item: item_values});
 
+        channel.push({item: item_values});
     });
 
     let _attr = {

test/expectedOutput/relatedItem.xml

@@ -1 +1 @@
-<rss xmlns:yandex="http://news.yandex.ru" xmlns:media="http://search.yahoo.com/mrss/" xmlns:turbo="http://turbo.yandex.ru" version="2.0"><channel><title><![CDATA[title]]></title><link>http://example.com/rss.xml</link><description><![CDATA[description]]></description><language>ru</language><item turbo="true"><link>http://example.com/article4?this&amp;that</link><turbo:source>http://example.com/article4?this&amp;that</turbo:source><pubDate>Sat, 26 May 2012 21:00:00 GMT</pubDate><author>LightAir</author><turbo:content><![CDATA[<header><figure><img src="http://example.com/example.png" /></figure> <h1>item title</h1></header><p>hello</p>]]></turbo:content><yandex:related>&lt;link url=&quot;http://example.com/related/post1&quot; img=&quot;http://example.com/i/img1.jpg&quot;&gt;related link text 1&lt;/link&gt;&lt;link url=&quot;http://example.com/related/post2&quot; img=&quot;http://example.com/i/img2.jpg&quot;&gt;related link text 2&lt;/link&gt;</yandex:related></item></channel></rss>
+<rss xmlns:yandex="http://news.yandex.ru" xmlns:media="http://search.yahoo.com/mrss/" xmlns:turbo="http://turbo.yandex.ru" version="2.0"><channel><title><![CDATA[title]]></title><link>http://example.com/rss.xml</link><description><![CDATA[description]]></description><language>ru</language><item turbo="true"><link>http://example.com/article4?this&amp;that</link><turbo:source>http://example.com/article4?this&amp;that</turbo:source><pubDate>Sat, 26 May 2012 21:00:00 GMT</pubDate><author>LightAir</author><turbo:content><![CDATA[<header><figure><img src="http://example.com/example.png" /></figure> <h1>item title</h1></header><p>hello</p>]]></turbo:content><yandex:related><link url="http://example.com/related/post1" img="http://example.com/i/img1.jpg">related link text 1</link><link url="http://example.com/related/post2" img="http://example.com/i/img2.jpg">related link text 2</link></yandex:related></item></channel></rss>