diff --git a/Library/Phalcon/Mvc/Model/Behavior/NestedSet.php b/Library/Phalcon/Mvc/Model/Behavior/NestedSet.php
index 2d8518a17..b1a709f56 100644
--- a/Library/Phalcon/Mvc/Model/Behavior/NestedSet.php
+++ b/Library/Phalcon/Mvc/Model/Behavior/NestedSet.php
@@ -9,9 +9,21 @@
 use Phalcon\Db\AdapterInterface;
 use Phalcon\Mvc\Model\BehaviorInterface;
 use Phalcon\Mvc\Model\ResultsetInterface;
+use Phalcon\Traits\EventManagerAwareTrait;
 
 class NestedSet extends Behavior implements BehaviorInterface
 {
+    use EventManagerAwareTrait;
+
+    const EVT_TYPE_QUERY = 'nestedset';
+
+    const EVT_DESCENDANTS = 'Descendants';
+    const EVT_ANCESTORS = 'Ancestors';
+    const EVT_PARENT = 'Parent';
+    const EVT_PREV = 'Prev';
+    const EVT_NEXT = 'Next';
+    const EVT_ROOTS = 'Roots';
+
     /**
      * @var AdapterInterface|null
      */
@@ -216,6 +228,16 @@ public function descendants($depth = null, $addSelf = false)
             $query = $query->andWhere($this->rootAttribute . '=' . $owner->{$this->rootAttribute});
         }
 
+        $this->fire(
+            self::EVT_TYPE_QUERY . ':before' . self::EVT_DESCENDANTS,
+            $query,
+            [
+                'owner' => $owner,
+                'depth' => $depth,
+                'addSelf' => $addSelf
+            ]
+        );
+
         return $query->execute();
     }
 
@@ -252,6 +274,15 @@ public function ancestors($depth = null)
             $query = $query->andWhere($this->rootAttribute . '=' . $owner->{$this->rootAttribute});
         }
 
+        $this->fire(
+            self::EVT_TYPE_QUERY . ':before' . self::EVT_ANCESTORS,
+            $query,
+            [
+                'owner' => $owner,
+                'depth' => $depth
+            ]
+        );
+
         return $query->execute();
     }
 
@@ -264,7 +295,19 @@ public function roots()
     {
         $owner = $this->getOwner();
 
-        return $owner::find($this->leftAttribute . ' = 1');
+        $query = $owner::query()
+            ->andWhere($this->leftAttribute . ' = 1')
+        ;
+
+        $this->fire(
+            self::EVT_TYPE_QUERY . ':before' . self::EVT_ROOTS,
+            $query,
+            [
+                'owner' => $owner
+            ]
+        );
+
+        return $owner::find($query->getParams());
     }
 
     /**
@@ -286,6 +329,14 @@ public function parent()
             $query = $query->andWhere($this->rootAttribute . '=' . $owner->{$this->rootAttribute});
         }
 
+        $this->fire(
+            self::EVT_TYPE_QUERY . ':before' . self::EVT_PARENT,
+            $query,
+            [
+                'owner' => $owner
+            ]
+        );
+
         return $query->execute()->getFirst();
     }
 
@@ -304,6 +355,14 @@ public function prev()
             $query = $query->andWhere($this->rootAttribute . '=' . $owner->{$this->rootAttribute});
         }
 
+        $this->fire(
+            self::EVT_TYPE_QUERY . ':before' . self::EVT_PREV,
+            $query,
+            [
+                'owner' => $owner
+            ]
+        );
+
         return $query->execute()->getFirst();
     }
 
@@ -322,6 +381,14 @@ public function next()
             $query = $query->andWhere($this->rootAttribute . '=' . $owner->{$this->rootAttribute});
         }
 
+        $this->fire(
+            self::EVT_TYPE_QUERY . ':before' . self::EVT_NEXT,
+            $query,
+            [
+                'owner' => $owner
+            ]
+        );
+
         return $query->execute()->getFirst();
     }
 
diff --git a/Library/Phalcon/Traits/EventManagerTrait.php b/Library/Phalcon/Traits/EventManagerTrait.php
new file mode 100644
index 000000000..681a6e4bb
--- /dev/null
+++ b/Library/Phalcon/Traits/EventManagerTrait.php
@@ -0,0 +1,85 @@
+<?php
+
+/*
+  +------------------------------------------------------------------------+
+  | Phalcon Framework                                                      |
+  +------------------------------------------------------------------------+
+  | Copyright (c) 2011-2017 Phalcon Team (https://www.phalconphp.com)      |
+  +------------------------------------------------------------------------+
+  | This source file is subject to the New BSD License that is bundled     |
+  | with this package in the file LICENSE.txt.                             |
+  |                                                                        |
+  | If you did not receive a copy of the license and are unable to         |
+  | obtain it through the world-wide-web, please send an email             |
+  | to license@phalconphp.com so we can send you a copy immediately.       |
+  +------------------------------------------------------------------------+
+  | Authors: Sergii Svyrydenko <sergey.v.sviridenko@gmail.com>             |
+  +------------------------------------------------------------------------+
+*/
+
+namespace Phalcon\Traits;
+
+use Phalcon\Di;
+use Phalcon\Events\Manager as EventsManager;
+
+/**
+ * Phalcon\Traits\EventManagerAwareTrait
+ *
+ * Trait for event processing
+ *
+ * @package Phalcon\Traits
+ */
+
+trait EventManagerAwareTrait
+{
+    /**
+     * @var EventsManager
+     */
+    protected $eventsManager = null;
+
+    /**
+     * set event manager
+     *
+     * @param EventsManager $eventsManager
+     */
+    public function setEventsManager(EventsManager $manager)
+    {
+        $this->eventsManager = $manager;
+    }
+
+    /**
+     * return event manager
+     *
+     * @return EventsManager | null
+     */
+    public function getEventsManager()
+    {
+        if (!empty($this->eventsManager)) {
+            $manager =  $this->eventsManager;
+        } elseif (Di::getDefault()->has('eventsManager')) {
+            $manager = Di::getDefault()->get('eventsManager');
+        }
+
+        if (isset($manager) && $manager instanceof EventsManager) {
+            return $manager;
+        }
+
+        return null;
+    }
+
+    /**
+     * Checking if event manager is defined - fire event
+     *
+     * @param string $event
+     * @param object $source
+     * @param mixed $data
+     * @param boolean $cancelable
+     *
+     */
+    public function fire($event, $source, $data = null, $cancelable = true)
+    {
+        if ($manager = $this->getEventsManager()) {
+            $manager->fire($event, $source, $data, $cancelable);
+        }
+    }
+}
diff --git a/composer.json b/composer.json
index 70baa0a28..4f6bb6c0f 100644
--- a/composer.json
+++ b/composer.json
@@ -39,7 +39,7 @@
         "phpunit/phpunit": "^4.8",
         "squizlabs/php_codesniffer": "^2.9",
         "codeception/codeception": "^2.3",
-        "codeception/mockery-module": "^0.2",
+        "codeception/mockery-module": "0.2.2",
         "codeception/aerospike-module": "^1.0",
         "codeception/specify": "^0.4",
         "codeception/verify": "^0.3",
diff --git a/tests/_ci/install_prereqs_5.sh b/tests/_ci/install_prereqs_5.sh
index 734bc3ea9..7614eb9a1 100644
--- a/tests/_ci/install_prereqs_5.sh
+++ b/tests/_ci/install_prereqs_5.sh
@@ -14,7 +14,7 @@
 printf "\n" | pecl install --force apcu-4.0.11 &> /dev/null
 printf "\n" | pecl install --force igbinary &> /dev/null
 printf "\n" | pecl install --force imagick &> /dev/null
-printf "\n" | pecl install --force yaml &> /dev/null
+printf "\n" | pecl install --force yaml-1.3.1 &> /dev/null
 
 echo 'extension="mongo.so"' >> "$(phpenv root)/versions/$(phpenv version-name)/etc/php.ini"
 echo 'extension="mongodb.so"' >> "$(phpenv root)/versions/$(phpenv version-name)/etc/php.ini"