Add test

[MAILPOET-1571]

lib/Models/NewsletterLink.php

@@ -5,4 +5,19 @@ if(!defined('ABSPATH')) exit;
 
 class NewsletterLink extends Model {
   public static $_table = MP_NEWSLETTER_LINKS_TABLE;
+
+  static function findTopLinkForNewsletter(Newsletter $newsletter) {
+    return self::selectExpr('links.*')
+      ->selectExpr('count(*)', 'clicksCount')
+      ->tableAlias('links')
+      ->innerJoin(StatisticsClicks::$_table,
+        array('clicks.link_id', '=', 'links.id'),
+        'clicks')
+      ->where('newsletter_id', $newsletter->id())
+      ->groupBy('links.id')
+      ->orderByDesc('clicksCount')
+      ->limit(1)
+      ->findOne();
+  }
+
 }