Test that reflects the issue described in http://www.doctrine-project.org/jira/browse/DDC-3967

tests/Doctrine/Tests/ORM/Functional/Ticket/DDC3967Test.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\Tests\Models\Cache\Country;
+use Doctrine\Tests\ORM\Functional\SecondLevelCacheAbstractTest;
+
+class DDC3967Test extends SecondLevelCacheAbstractTest
+{
+    protected function setUp()
+    {
+        parent::setUp();
+
+        $this->loadFixturesCountries();
+        $this->_em->getCache()->evictEntityRegion(Country::CLASSNAME);
+        $this->_em->clear();
+    }
+
+    public function testIdentifierCachedWithProperType()
+    {
+        $country = array_pop($this->countries);
+        $id = $country->getId();
+
+        // First time, loaded from database
+        $this->_em->find(Country::CLASSNAME, "$id");
+        $this->_em->clear();
+
+        // Second time, loaded from cache
+        /** @var Country $country */
+        $country = $this->_em->find(Country::CLASSNAME, "$id");
+
+        // Identifier type should be integer
+        $this->assertSame($country->getId(), $id);
+    }
+}