test the DoctrineObject hydrator factory

tests/DoctrineMongoODMModuleTest/Doctrine/DoctrineObjectHydratorFactoryTest.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace DoctrineMongoODMModuleTest\Doctrine;
+
+use Doctrine\ODM\MongoDB\DocumentManager;
+use DoctrineModule\Stdlib\Hydrator\DoctrineObject;
+use PHPUnit_Framework_TestCase as TestCase;
+use DoctrineMongoODMModule\Service\DoctrineObjectHydratorFactory;
+use Zend\ServiceManager\ServiceLocatorInterface;
+use Zend\Stdlib\Hydrator\HydratorPluginManager;
+
+class DoctrineObjectHydratorFactoryTest extends TestCase
+{
+    public function testReturnsHydratorInstance()
+    {
+        $serviceLocatorInterface = $this->getMock(ServiceLocatorInterface::class);
+
+        $serviceLocatorInterface
+            ->expects($this->once())
+            ->method('get')
+            ->with('doctrine.documentmanager.odm_default')
+            ->willReturn(
+                $this->getMockBuilder(DocumentManager::class)
+                     ->disableOriginalConstructor()
+                     ->getMock()
+            );
+
+        /** @var HydratorPluginManager $hydratorPluginManager */
+        $hydratorPluginManager = $this->getMock(HydratorPluginManager::class);
+
+        $hydratorPluginManager
+            ->expects($this->once())
+            ->method('getServiceLocator')
+            ->willReturn(
+                $serviceLocatorInterface
+            );
+
+
+        $factory  = new DoctrineObjectHydratorFactory();
+        $hydrator = $factory($hydratorPluginManager);
+
+        $this->assertInstanceOf(DoctrineObject::class, $hydrator);
+    }
+}