diff --git a/README.md b/README.md
index 4063c04..a277a86 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ Add the following to your `composer.json` file:
 
 ```
 "require": {
-    "matryoshka-model/mongo-wrapper": "~0.7.0"
+    "matryoshka-model/mongo-wrapper": "~0.8.0"
 }
 ```
 
@@ -97,6 +97,12 @@ It's important to always use the `HydratingResultSet` class included in this pac
 
 - `Matryoshka\Model\Wrapper\Mongo\Service` contains abstract service factories generally aimed at instantiation of `\MongoCollection` and `\MongoDb` objects. Use `mongocollection` and `mongodb` configuration nodes to respectively setup them (see [above](#configuration)).
 
+## Continuous integration
+
+**CI** provided through [TravisCI](http://travis-ci.org/matryoshka-model/mongo-wrapper).
+
+This wrapper is tested against the following MongoDB PHP clients: **1.4.5**, **1.5.0**, **1.5.1**, **1.5.2**, **1.5.3**, **1.5.3**, **1.5.5**, **1.5.6**, **1.5.7**, **1.5.8**, **1.6.0**, **1.6.1**, **1.6.2**, **1.6.3**, **1.6.4**, **1.6.5**, **1.6.6**, **1.6.7**, **1.6.8**, **1.6.9**.
+
 ---
 
 [![Analytics](https://ga-beacon.appspot.com/UA-49657176-2/mongo-wrapper?flat)](https://github.com/igrigorik/ga-beacon)
diff --git a/composer.json b/composer.json
index 9d7ccf6..926cb08 100644
--- a/composer.json
+++ b/composer.json
@@ -6,7 +6,7 @@
     "require": {
         "php": ">=5.5.0",
         "ext-mongo": "*",
-        "matryoshka-model/matryoshka": "0.8.*@dev",
+        "matryoshka-model/matryoshka": "~0.8.0",
         "zendframework/zend-stdlib": "2.*",
         "zendframework/zend-paginator": "2.*",
         "zendframework/zend-servicemanager": "2.*"
@@ -40,10 +40,17 @@
     ],
     "autoload": {
         "psr-4": {
-        	"Matryoshka\\Model\\Wrapper\\Mongo\\": "library/",
-        	"MatryoshkaModelWrapperMongoTest\\": "tests/"
+        	"Matryoshka\\Model\\Wrapper\\Mongo\\": "library/"
         }
     },
+    "autoload-dev": {
+        "psr-4": {
+        	"MatryoshkaModelWrapperMongoTest\\": "tests/"
+        },
+        "files": [
+        	"tests/TestAsset/MongoCollectionMockProxy.php"
+        ]
+    },
     "keywords": [
         "model",
         "matryoshka",
@@ -63,6 +70,7 @@
     "suggest": {
         "matryoshka-model/matryoshka": "A lightweight framework that provides a standard and easy way to implement a model service layer",
         "matryoshka-model/zf2-matryoshka-module": "ZF2 module for matryoshka library",
-        "matryoshka-model/rest-wrapper": "Matryoshka wrapper aimed at creating restful API clients"
+        "matryoshka-model/rest-wrapper": "Matryoshka wrapper aimed at creating restful API clients",
+        "matryoshka-model/mongo-transactional": "Perform transactional operations with MongoDB"
     }
 }
diff --git a/library/Criteria/ActiveRecord/ActiveRecordCriteria.php b/library/Criteria/ActiveRecord/ActiveRecordCriteria.php
index 4eb5162..7cb7a7a 100644
--- a/library/Criteria/ActiveRecord/ActiveRecordCriteria.php
+++ b/library/Criteria/ActiveRecord/ActiveRecordCriteria.php
@@ -12,7 +12,6 @@
 use Matryoshka\Model\Exception;
 use Matryoshka\Model\ModelStubInterface;
 use Matryoshka\Model\Wrapper\Mongo\Criteria\HandleResultTrait;
-use Zend\Stdlib\Hydrator\AbstractHydrator;
 
 /**
  * Class ActiveRecordCriteria
@@ -35,23 +34,27 @@ class ActiveRecordCriteria extends AbstractCriteria
     /**
      * @var array
      */
-    protected $saveOptions = [];
+    protected $mongoOptions = [];
 
     /**
+     * Get options for Mongo save and remove operations
+     *
      * @return array
      */
-    public function getSaveOptions()
+    public function getMongoOptions()
     {
-        return $this->saveOptions;
+        return $this->mongoOptions;
     }
 
     /**
+     * Set options for Mongo save and remove operations
+     *
      * @param array $options
      * @return $this
      */
-    public function setSaveOptions(array $options)
+    public function setMongoOptions(array $options)
     {
-        $this->saveOptions = $options;
+        $this->mongoOptions = $options;
         return $this;
     }
 
@@ -76,14 +79,16 @@ public function applyWrite(ModelStubInterface $model, array &$data)
         /** @var $dataGateway \MongoCollection */
         $dataGateway = $model->getDataGateway();
 
-        unset($data['_id']);
-
-        if ($this->id) {
+        if ($this->hasId()) {
             $data['_id'] = $this->extractId($model);
         }
 
+        if (array_key_exists('_id', $data) && null === $data['_id']) {
+            unset($data['_id']);
+        }
+
         $tmp = $data;  // passing a referenced variable to save will fail in update the content
-        $result = $dataGateway->save($tmp, $this->getSaveOptions());
+        $result = $dataGateway->save($tmp, $this->getMongoOptions());
         $data = $tmp;
         return $this->handleResult($result);
     }
@@ -93,7 +98,10 @@ public function applyWrite(ModelStubInterface $model, array &$data)
      */
     public function applyDelete(ModelStubInterface $model)
     {
-        $result = $model->getDataGateway()->remove(['_id' => $this->extractId($model)]);
+        $result = $model->getDataGateway()->remove(
+            ['_id' => $this->extractId($model)],
+            ['justOne' => true] + $this->getMongoOptions()
+        );
         return $this->handleResult($result, true);
     }
 
@@ -103,11 +111,13 @@ public function applyDelete(ModelStubInterface $model)
      */
     protected function extractId(ModelStubInterface $model)
     {
-        if (!$model->getHydrator() instanceof AbstractHydrator) {
+        $hydrator = $model->getHydrator();
+        if (!method_exists($hydrator, 'extractValue')) {
             throw new Exception\RuntimeException(
-                'Hydrator must be an instance of \Zend\Stdlib\Hydrator\AbstractHydrator'
-            );
+                'Hydrator must have extractValue() method ' .
+                'in order to extract a single value'
+                );
         }
-        return $model->getHydrator()->extractValue('_id', $this->getId());
+        return $hydrator->extractValue('_id', $this->getId());
     }
 }
diff --git a/library/Criteria/FindAllCriteria.php b/library/Criteria/FindAllCriteria.php
index e97a7ed..9f1cc7a 100644
--- a/library/Criteria/FindAllCriteria.php
+++ b/library/Criteria/FindAllCriteria.php
@@ -14,7 +14,6 @@
 use Matryoshka\Model\Exception\InvalidArgumentException;
 use Matryoshka\Model\ModelStubInterface;
 use Matryoshka\Model\Wrapper\Mongo\Paginator\MongoPaginatorAdapter;
-use Zend\Stdlib\Hydrator\AbstractHydrator;
 
 /**
  * Class FindAllCriteria
@@ -111,17 +110,15 @@ public function setOrderBy(array $orders = [])
      */
     protected function extractValue(ModelStubInterface $model, $name, $value, $object = null)
     {
-        if (!$model->getHydrator() instanceof AbstractHydrator) {
+        $hydrator = $model->getHydrator();
+        if (!method_exists($hydrator, 'extractValue')) {
             throw new Exception\RuntimeException(
-                sprintf(
-                    'Hydrator must be an instance of "%s"; detected "%s"',
-                    '\Zend\Stdlib\Hydrator\AbstractHydrator',
-                    get_class($model->getHydrator())
-                )
-            );
+                'Hydrator must have extractValue() method ' .
+                'in order to extract a single value'
+                );
         }
 
-        return $model->getHydrator()->extractValue($name, $value, $object);
+        return $hydrator->extractValue($name, $value, $object);
     }
 
     /**
diff --git a/library/Criteria/Isolated/ActiveRecordCriteria.php b/library/Criteria/Isolated/ActiveRecordCriteria.php
index e5ffc43..2fca47f 100644
--- a/library/Criteria/Isolated/ActiveRecordCriteria.php
+++ b/library/Criteria/Isolated/ActiveRecordCriteria.php
@@ -39,16 +39,18 @@ public function apply(ModelStubInterface $model)
      */
     public function applyWrite(ModelStubInterface $model, array &$data)
     {
-        unset($data['_id']);
-
-        if ($this->id) {
+        if ($this->hasId()) {
             $data['_id'] = $this->extractId($model);
         }
 
+        if (array_key_exists('_id', $data) && null === $data['_id']) {
+            unset($data['_id']);
+        }
+
         return $this->getDocumentStore()->isolatedUpsert(
             $model->getDataGateway(),
             $data,
-            $this->getSaveOptions()
+            $this->getMongoOptions()
         );
     }
 
@@ -60,7 +62,8 @@ public function applyDelete(ModelStubInterface $model)
     {
         return $this->getDocumentStore()->isolatedRemove(
             $model->getDataGateway(),
-            $this->extractId($model)
+            $this->extractId($model),
+            $this->getMongoOptions()
         );
     }
 }
diff --git a/library/Criteria/Isolated/DocumentStore.php b/library/Criteria/Isolated/DocumentStore.php
index 0291f74..6bcf414 100644
--- a/library/Criteria/Isolated/DocumentStore.php
+++ b/library/Criteria/Isolated/DocumentStore.php
@@ -230,7 +230,7 @@ public function isolatedUpsert(MongoCollection $dataGateway, array &$data, array
                 $oldDocumentData,
                 $data, // modifiers and non-modifiers cannot be mixed,
                 // the _id presence ensure at least one non-modifiers
-                array_merge($options, ['multi' => false, 'upsert' => false])
+                ['multi' => false, 'upsert' => false] + $options
             );
             $result = $this->handleResult($result);
 
@@ -258,7 +258,7 @@ public function isolatedRemove(MongoCollection $dataGateway, $id, array $options
             throw new RuntimeException(sprintf('No local copy found for the document "%s"', $id));
         }
 
-        $result = $dataGateway->remove($this->get($dataGateway, $id), $options);
+        $result = $dataGateway->remove($this->get($dataGateway, $id), ['justOne' => true] + $options);
         $result = $this->handleResult($result, true);
 
         if ($result != 1) {
diff --git a/library/Hydrator/Strategy/MongoBinDataStrategy.php b/library/Hydrator/Strategy/MongoBinDataStrategy.php
index 90f6086..f35594c 100644
--- a/library/Hydrator/Strategy/MongoBinDataStrategy.php
+++ b/library/Hydrator/Strategy/MongoBinDataStrategy.php
@@ -8,13 +8,19 @@
  */
 namespace Matryoshka\Model\Wrapper\Mongo\Hydrator\Strategy;
 
+use MongoBinData;
 use Zend\Stdlib\Hydrator\Strategy\StrategyInterface;
+use Matryoshka\Model\Hydrator\Strategy\NullableStrategyTrait;
+use Matryoshka\Model\Hydrator\Strategy\NullableStrategyInterface;
+use Matryoshka\Model\Exception;
 
 /**
  * Class MongoBinDataStrategy
  */
-class MongoBinDataStrategy implements StrategyInterface
+class MongoBinDataStrategy implements StrategyInterface, NullableStrategyInterface
 {
+    use NullableStrategyTrait;
+    
     /**
      * @var int
      */
@@ -45,24 +51,41 @@ public function setType($type)
         $this->type = (int) $type;
         return $this;
     }
-
+    
     /**
-     * Ensure the value extracted is typed as \MongoBinData or null
-     *
+     * Convert a MongoBinData to binary string
+     * 
      * @param mixed $value The original value.
-     * @return null|\MongoBinData Returns the value that should be extracted.
+     * @return null|string Returns the value that should be hydrated.
      */
-    public function extract($value)
+    public function hydrate($value)
     {
-        return null === $value ? null : new \MongoBinData($value, $this->type);
+        if ($this->nullable && $value === null) {
+            return null;
+        }
+        
+        if ($value instanceof MongoBinData) {
+            return $value->bin;
+        }
+        
+        throw new Exception\InvalidArgumentException(sprintf(
+            'Invalid value: must be an instance of MongoBinData, "%s" given',
+            is_object($value) ? get_class($value) : gettype($value)
+        ));
     }
 
     /**
+     * Ensure the value extracted is typed as MongoBinData or null
+     *
      * @param mixed $value The original value.
-     * @return null|string Returns the value that should be hydrated.
+     * @return null|\MongoBinData Returns the value that should be extracted.
      */
-    public function hydrate($value)
+    public function extract($value)
     {
-        return $value instanceof \MongoBinData ? $value->bin : null;
+        if ($this->nullable && $value === null) {
+            return null;
+        }
+        
+        return new MongoBinData($value, $this->type);
     }
 }
diff --git a/library/Hydrator/Strategy/MongoDateStrategy.php b/library/Hydrator/Strategy/MongoDateStrategy.php
index 6a44b0c..729301b 100644
--- a/library/Hydrator/Strategy/MongoDateStrategy.php
+++ b/library/Hydrator/Strategy/MongoDateStrategy.php
@@ -11,12 +11,17 @@
 use DateTime;
 use MongoDate;
 use Zend\Stdlib\Hydrator\Strategy\StrategyInterface;
+use Matryoshka\Model\Hydrator\Strategy\NullableStrategyInterface;
+use Matryoshka\Model\Hydrator\Strategy\NullableStrategyTrait;
+use Matryoshka\Model\Exception;
 
 /**
  * Class MongoDateStrategy
  */
-class MongoDateStrategy implements StrategyInterface
+class MongoDateStrategy implements StrategyInterface, NullableStrategyInterface
 {
+    use NullableStrategyTrait;
+    
     /**
      * @var string
      */
@@ -34,34 +39,53 @@ public function __construct($format = null)
         }
     }
 
+    
     /**
+     * Convert a MongoDate to a DateTime
+     * 
      * @param mixed $value
-     * @return DateTime|mixed
+     * @return mixed|MongoDate
      */
-    public function extract($value)
+    public function hydrate($value)
     {
-        if ($value instanceof DateTime) {
-            $value = new MongoDate($value->format('U'));
-        } else {
-            $value = null;
+        if ($value instanceof MongoDate) {
+            return new DateTime(date($this->getFormat(), $value->sec));
+        } 
+        
+        if ($this->nullable && $value === null) {
+            return null;
         }
-        return $value;
+        
+        throw new Exception\InvalidArgumentException(sprintf(
+            'Invalid value: must be an instance of MongoDate, "%s" given.',
+            is_object($value) ? get_class($value) : gettype($value)
+        ));
     }
-
+    
+    
     /**
+     * Convert a DateTime to a MongoDate
+     * 
      * @param mixed $value
-     * @return mixed|MongoDate
+     * @return DateTime|mixed
      */
-    public function hydrate($value)
+    public function extract($value)
     {
-        if ($value instanceof MongoDate) {
-            $value = new DateTime(date($this->getFormat(), $value->sec));
-        } else {
-            $value = null;
+        if ($value instanceof DateTime) {
+            return new MongoDate($value->format('U'));
+        }
+        
+        if ($this->nullable && $value === null) {
+            return null;
         }
-        return $value;
+        
+        throw new Exception\InvalidArgumentException(sprintf(
+            'Invalid value: must be an instance of DateTime, "%s" given.',
+            is_object($value) ? get_class($value) : gettype($value)
+        ));
     }
 
+
     /**
      * @param string $format
      * @return $this
diff --git a/library/Hydrator/Strategy/MongoIdStrategy.php b/library/Hydrator/Strategy/MongoIdStrategy.php
index b6bd254..c050292 100644
--- a/library/Hydrator/Strategy/MongoIdStrategy.php
+++ b/library/Hydrator/Strategy/MongoIdStrategy.php
@@ -8,32 +8,61 @@
  */
 namespace Matryoshka\Model\Wrapper\Mongo\Hydrator\Strategy;
 
+use MongoId;
 use Zend\Stdlib\Hydrator\Strategy\StrategyInterface;
+use Matryoshka\Model\Hydrator\Strategy\NullableStrategyTrait;
+use Matryoshka\Model\Hydrator\Strategy\NullableStrategyInterface;
+use Matryoshka\Model\Exception;
 
 /**
  * Class MongoIdStrategy
  */
-class MongoIdStrategy implements StrategyInterface
+class MongoIdStrategy implements StrategyInterface, NullableStrategyInterface
 {
+    use NullableStrategyTrait;
+    
     /**
-     * Ensure the value extracted is typed as \MongoId or null
+     * Ensure the value extracted is typed as string or null
      *
      * @param mixed $value The original value.
-     * @return null|\MongoId Returns the value that should be extracted.
+     * @return null|string Returns the value that should be hydrated.
      */
-    public function extract($value)
+    public function hydrate($value)
     {
-        return null === $value ? null : new \MongoId($value);
+        if ($value instanceof MongoId) {
+            return (string)$value;
+        }
+        
+        if ($this->nullable && $value === null) {
+            return null;
+        }
+        
+        throw new Exception\InvalidArgumentException(sprintf(
+            'Invalid value: must be an instance of MongoId, "%s" given.',
+            is_object($value) ? get_class($value) : gettype($value)
+        ));
     }
-
+    
+    
     /**
-     * Ensure the value extracted is typed as string or null
-     * 
+     * Ensure the value extracted is typed as MongoId or null
+     *
      * @param mixed $value The original value.
-     * @return null|string Returns the value that should be hydrated.
+     * @return null|MongoId Returns the value that should be extracted.
      */
-    public function hydrate($value)
+    public function extract($value)
     {
-        return $value === null ? null : (string)$value;
+        if (is_string($value)) {
+            return new MongoId($value);
+        }
+        
+        if ($this->nullable && $value === null) {
+            return null;
+        }
+        
+        throw new Exception\InvalidArgumentException(sprintf(
+            'Invalid value: must be a string containing a valid mongo ID, "%s" given.',
+            is_object($value) ? get_class($value) : gettype($value)
+        ));
     }
 }
diff --git a/tests/Criteria/ActiveRecord/ActiveRecordCriteriaTest.php b/tests/Criteria/ActiveRecord/ActiveRecordCriteriaTest.php
index b0f677a..b761a0a 100644
--- a/tests/Criteria/ActiveRecord/ActiveRecordCriteriaTest.php
+++ b/tests/Criteria/ActiveRecord/ActiveRecordCriteriaTest.php
@@ -20,19 +20,6 @@
  */
 class ActiveRecordCriteriaTest extends \PHPUnit_Framework_TestCase
 {
-    protected static $oldErrorLevel;
-
-    protected static function disableStrictErrors()
-    {
-        self::$oldErrorLevel = error_reporting();
-        error_reporting(self::$oldErrorLevel & ~E_STRICT);
-    }
-
-    protected static function restoreErrorReportingLevel()
-    {
-        error_reporting(self::$oldErrorLevel);
-    }
-
     /**
      * @var Model
      */
@@ -50,10 +37,8 @@ public function setUp()
 
         $this->mongoCollectionMock = $mongoCollectionMock;
 
-        self::disableStrictErrors();
-        $mockProxy = new MongoCollectionMockProxy();
-        self::restoreErrorReportingLevel();
-        $mockProxy->__MongoCollectionMockProxy__setMock($mongoCollectionMock);
+        $mockProxy = new MongoCollectionMockProxy;
+        $mockProxy->__MongoCollectionMockProxy__setMock($this->mongoCollectionMock);
 
         $rs = new ArrayObjectResultSet();
         $model = new Model($mockProxy, $rs);
@@ -90,13 +75,15 @@ public function testApply()
 
     public function testApplyWrite()
     {
+        $options = ['foo' => 'baz'];
         $ar = new ActiveRecordCriteria();
+        $ar->setMongoOptions($options);
         $testId = 1;
         $testData = ['_id' => $testId];
 
         $this->mongoCollectionMock->expects($this->at(0))
             ->method('save')
-            ->with($this->equalTo($testData), $this->equalTo($ar->getSaveOptions()));
+            ->with($this->equalTo($testData), $this->equalTo($options));
 
 
         $ar->setId($testId);
@@ -129,30 +116,33 @@ public function testApplyWriteWithoutId()
 
         $this->mongoCollectionMock->expects($this->at(0))
             ->method('save')
-            ->with($this->equalTo($testUnsetData), $this->equalTo($ar->getSaveOptions()));
+            ->with($this->equalTo($testUnsetData), $this->equalTo($ar->getMongoOptions()));
 
         $ar->applyWrite($this->model, $testData);
         $this->assertInstanceOf('\MongoId', $testData['_id']);
     }
 
-    public function testSaveOptions()
+    public function testGetSetMongoOptions()
     {
-        $saveOptions = ['foo', 'bar'];
         $ar = new ActiveRecordCriteria();
-        $ar->setSaveOptions($saveOptions);
+        $this->assertEmpty($ar->getMongoOptions());
 
-        $this->assertEquals($saveOptions, $ar->getSaveOptions());
+        $saveOptions = ['foo', 'bar'];
+        $ar->setMongoOptions($saveOptions);
+        $this->assertEquals($saveOptions, $ar->getMongoOptions());
     }
 
     public function testApplyDelete()
     {
+        $options = ['foo' => 'baz'];
         $ar = new ActiveRecordCriteria();
+        $ar->setMongoOptions($options);
         $testId = 1;
         $testData = ['_id' => $testId];
 
         $this->mongoCollectionMock->expects($this->at(0))
             ->method('remove')
-            ->with($this->equalTo($testData));
+            ->with($this->equalTo($testData), $this->equalTo(['justOne' => true] + $options));
 
 
         $ar->setId($testId);
diff --git a/tests/Criteria/Isolated/ActiveRecordCriteriaTest.php b/tests/Criteria/Isolated/ActiveRecordCriteriaTest.php
index 7eecd19..d984837 100644
--- a/tests/Criteria/Isolated/ActiveRecordCriteriaTest.php
+++ b/tests/Criteria/Isolated/ActiveRecordCriteriaTest.php
@@ -20,26 +20,12 @@
  */
 class ActiveRecordCriteriaTest extends \PHPUnit_Framework_TestCase
 {
-    protected static $oldErrorLevel;
-
-    protected static function disableStrictErrors()
-    {
-        self::$oldErrorLevel = error_reporting();
-        error_reporting(self::$oldErrorLevel & ~E_STRICT);
-    }
-
-    protected static function restoreErrorReportingLevel()
-    {
-        error_reporting(self::$oldErrorLevel);
-    }
 
     protected static $sharedDataGateway;
 
     public static function setUpBeforeClass()
     {
-        self::disableStrictErrors();
         self::$sharedDataGateway = new MongoCollectionMockProxy();
-        self::restoreErrorReportingLevel();
     }
 
     /** @var \PHPUnit_Framework_MockObject_MockObject $mongoCollectionMock */
@@ -165,7 +151,7 @@ public function testApplyWrite()
 
         $this->mongoCollectionMock->expects($this->atLeastOnce())
             ->method('insert')
-            ->with($this->equalTo($expectedResult), $this->equalTo($criteria->getSaveOptions()))
+            ->with($this->equalTo($expectedResult), $this->equalTo($criteria->getMongoOptions()))
             ->will($this->returnValue(['ok' => true, 'n' => 0])); // MongoDB returns 0 on insert operation
 
         $criteria->setId($testId);
@@ -181,7 +167,7 @@ public function testApplyWrite()
             ->with(
                 $this->equalTo($currentDataState),
                 $this->equalTo($expectedResult),
-                $this->equalTo(array_merge($criteria->getSaveOptions(), ['multi' => false, 'upsert' => false]))
+                $this->equalTo(['multi' => false, 'upsert' => false] + $criteria->getMongoOptions())
             )
             ->will($this->returnValue(['ok' => true, 'n' => 1, 'updatedExisting' => true]));
 
@@ -190,9 +176,9 @@ public function testApplyWrite()
         $this->assertHasDocumentCache($testId, $expectedResult);
     }
 
-    /**
-     * @depends testApplyWrite
-     */
+//     /**
+//      * @depends testApplyWrite
+//      */
     public function testApplyWriteWithoutId()
     {
         $model    = $this->model;
@@ -202,7 +188,7 @@ public function testApplyWriteWithoutId()
         //Test insert
         $this->mongoCollectionMock->expects($this->atLeastOnce())
             ->method('insert')
-            ->with($this->equalTo($testData), $this->equalTo($criteria->getSaveOptions()))
+            ->with($this->equalTo($testData), $this->equalTo($criteria->getMongoOptions()))
             ->will($this->returnValue(['ok' => true, 'n' => 0])); // MongoDB returns 0 on insert operation
 
 
@@ -212,6 +198,26 @@ public function testApplyWriteWithoutId()
 
         $this->assertHasDocumentCache($testId, $testData);
     }
+    
+    public function testApplyWriteWithNullId()
+    {
+        $model    = $this->model;
+        $criteria = $this->criteria;
+        $dataWithoutId = ['test' => 'test']; 
+        $testData = array_merge($dataWithoutId, ['_id' => null]);
+    
+        //Test insert
+        $this->mongoCollectionMock->expects($this->atLeastOnce())
+            ->method('insert')
+            ->with($this->equalTo($dataWithoutId), $this->equalTo($criteria->getMongoOptions()))
+            ->will($this->returnValue(['ok' => true, 'n' => 0])); // MongoDB returns 0 on insert operation
+        $this->assertEquals(1, $criteria->applyWrite($model, $testData));
+        
+        $this->assertInstanceOf('\MongoId', $testData['_id']);
+        $testId = (string) $testData['_id'];
+    
+        $this->assertHasDocumentCache($testId, $testData);
+    }
 
     /**
      * @depends testApplyWriteWithoutId
diff --git a/tests/Criteria/Isolated/DocumentStoreTest.php b/tests/Criteria/Isolated/DocumentStoreTest.php
index 51a1a0a..814c192 100644
--- a/tests/Criteria/Isolated/DocumentStoreTest.php
+++ b/tests/Criteria/Isolated/DocumentStoreTest.php
@@ -16,19 +16,6 @@
  */
 class DocumentStoreTest extends \PHPUnit_Framework_TestCase
 {
-    protected static $oldErrorLevel;
-
-    protected static function disableStrictErrors()
-    {
-        self::$oldErrorLevel = error_reporting();
-        error_reporting(self::$oldErrorLevel & ~E_STRICT);
-    }
-
-    protected static function restoreErrorReportingLevel()
-    {
-        error_reporting(self::$oldErrorLevel);
-    }
-
     protected static $sharedDataGateway;
 
     /**
@@ -39,9 +26,7 @@ protected static function restoreErrorReportingLevel()
 
     public static function setUpBeforeClass()
     {
-        self::disableStrictErrors();
         self::$sharedDataGateway = new MongoCollectionMockProxy();
-        self::restoreErrorReportingLevel();
     }
 
     /** @var \PHPUnit_Framework_MockObject_MockObject $mongoCollectionMock */
@@ -295,7 +280,7 @@ public function testIsolatedRemove()
 
         $this->mongoCollectionMock->expects($this->atLeastOnce())
             ->method('remove')
-            ->with($this->equalTo($testData))
+            ->with($this->equalTo($testData), $this->equalTo(['justOne' => true] + $options))
             ->will($this->returnValue(['ok' => true, 'n' => 1]));
 
 
diff --git a/tests/Hydrator/Strategy/MongoBinDataTest.php b/tests/Hydrator/Strategy/MongoBinDataTest.php
index 6ee27de..361e3bd 100644
--- a/tests/Hydrator/Strategy/MongoBinDataTest.php
+++ b/tests/Hydrator/Strategy/MongoBinDataTest.php
@@ -9,6 +9,7 @@
 namespace MatryoshkaModelWrapperMongoTest\Hydrator\Strategy;
 
 use Matryoshka\Model\Wrapper\Mongo\Hydrator\Strategy\MongoBinDataStrategy;
+use Matryoshka\Model\Exception\InvalidArgumentException;
 
 /**
  * Class MongoBinDataTest
@@ -48,4 +49,13 @@ public function testHydrate()
         $result = $strategy->hydrate(null);
         $this->assertNull($result);
     }
+    
+    public function testHydrateShouldThrowExceptionWhenInvalidType()
+    {
+        $strategy = new MongoBinDataStrategy(\MongoBinData::CUSTOM);
+        $mongoBinData = new \MongoBinData('foo', \MongoBinData::CUSTOM);
+        
+        $this->setExpectedException(InvalidArgumentException::class);
+        $strategy->hydrate('invalid type');
+    }
 }
diff --git a/tests/Hydrator/Strategy/MongoDateStrategyTest.php b/tests/Hydrator/Strategy/MongoDateStrategyTest.php
index b7c929a..fac2bbc 100644
--- a/tests/Hydrator/Strategy/MongoDateStrategyTest.php
+++ b/tests/Hydrator/Strategy/MongoDateStrategyTest.php
@@ -9,6 +9,7 @@
 namespace MatryoshkaModelWrapperMongoTest\Hydrator\Strategy;
 
 use Matryoshka\Model\Wrapper\Mongo\Hydrator\Strategy\MongoDateStrategy;
+use Matryoshka\Model\Exception\InvalidArgumentException;
 
 /**
  * Class MongoDateStrategyTest
@@ -32,9 +33,11 @@ public function testExtract()
 
         $result = $strategy->extract(\DateTime::createFromFormat('U', $now));
         $this->assertEquals(new \MongoDate($now), $result);
+        
+        $this->assertNull($strategy->extract(null));
 
+        $this->setExpectedException(InvalidArgumentException::class);
         $result = $strategy->extract('test invalid value');
-        $this->assertNull($result);
     }
 
     public function testHydrate()
@@ -45,9 +48,11 @@ public function testHydrate()
 
         $result = $strategy->hydrate(new \MongoDate($now));
         $this->assertEquals(new \DateTime(date($format, $now)), $result);
+        
+        $this->assertNull($strategy->hydrate(null));
 
+        $this->setExpectedException(InvalidArgumentException::class);
         $result = $strategy->hydrate('test invalid value');
-        $this->assertNull($result);
     }
 
     public function testGetSetFormat()
diff --git a/tests/Hydrator/Strategy/MongoIdStrategyTest.php b/tests/Hydrator/Strategy/MongoIdStrategyTest.php
index 85b37a4..ddaaecb 100644
--- a/tests/Hydrator/Strategy/MongoIdStrategyTest.php
+++ b/tests/Hydrator/Strategy/MongoIdStrategyTest.php
@@ -9,6 +9,7 @@
 namespace MatryoshkaModelWrapperMongoTest\Hydrator\Strategy;
 
 use Matryoshka\Model\Wrapper\Mongo\Hydrator\Strategy\MongoIdStrategy;
+use Matryoshka\Model\Exception\InvalidArgumentException;
 
 /**
  * Class MongoIdStrategyTest
@@ -26,6 +27,9 @@ public function testExtract()
 
         $result = $strategy->extract(null);
         $this->assertNull($result);
+        
+        $this->setExpectedException(InvalidArgumentException::class);
+        $strategy->extract(['not-a-string' => 'invalid-type']);
     }
 
     public function testHydrate()
@@ -38,5 +42,9 @@ public function testHydrate()
 
         $result = $strategy->hydrate(null);
         $this->assertNull($result);
+        
+        $this->setExpectedException(InvalidArgumentException::class);
+        $strategy->hydrate('invalid-type');
     }
+
 }
diff --git a/tests/TestAsset/MongoCollectionMockProxy.php b/tests/TestAsset/MongoCollectionMockProxy.php
index 1e417bf..79bfdf4 100644
--- a/tests/TestAsset/MongoCollectionMockProxy.php
+++ b/tests/TestAsset/MongoCollectionMockProxy.php
@@ -1,359 +1,8 @@
 <?php
-/**
- * MongoDB matryoshka wrapper
- *
- * @link        https://github.com/matryoshka-model/mongo-wrapper
- * @copyright   Copyright (c) 2015, Ripa Club
- * @license     http://opensource.org/licenses/BSD-2-Clause Simplified BSD License
+/*
+ *  E_STRICT error reporting must be disabled due to incompatibile method signature with the original \MongoCollection class
  */
-namespace MatryoshkaModelWrapperMongoTest\TestAsset;
-
-/**
- * Class MongoCollectionMockProxy
- *
- * Proxy for \MongoCollection's mock in order to simulate the special behavior of insert() and save().
- *
- * MongoCollection::insert() and save() first parameter report the following specifications:
- * if the parameter does not have an _id key or property, a new MongoId instance will be created and assigned to it.
- * This special behavior does not mean that the parameter is passed by reference.
- *
- * The behavior can be simulated using parameter passed by reference but PHPUnit mock implementation doesn't allow that.
- * MongoCollectionMockProxy bypasses the issue changing the original method signature,
- * proxing the method call to the mock and finally adding the _id.
- *
- * NOTE: E_STRICT error reporting must be disabled due to incompatibile method signature with the parent class
- *
- * MongoCollection skeleton class by {@link https://github.com/localgod/PeclMongoPhpDoc}
- */
-class MongoCollectionMockProxy extends \MongoCollection
-{
-    protected $mock;
-
-    protected static $oldErrorLevel = null;
-
-    /**
-     * Ctor
-     *
-     * @param
-     */
-    public function __construct()
-    {
-        //won't call parent::__construct
-    }
-
-    public function __MongoCollectionMockProxy__setMock($mock)
-    {
-        $this->mock = $mock;
-    }
-
-    public function __set($name, $value)
-    {
-        return $this->mock->{$name} = $value;
-    }
-
-    public function __get($name)
-    {
-        return $this->mock->{$name};
-    }
-
-    public function __call($method, array $params)
-    {
-        if (count($params) > 0) {
-            return call_user_func_array([$this->mock, $method], $params);
-        }
-        return call_user_func([$this->mock, $method]);
-    }
-
-    /**
-     * Saves an object to this collection
-     *
-     * @link http://www.php.net/manual/en/mongocollection.save.php
-     * @param mixed $a
-     *            Array to save.
-     * @param array $options
-     *            Options for the save.
-     * @throws \MongoCursorException
-     * @return mixed
-     */
-    public function save(array &$a, array $options = [])
-    {
-        $return = $this->mock->save($a, $options);
-        if (!isset($a['_id']) || $a['_id'] === null) {
-            $a['_id'] = new \MongoId();
-        }
-        return $return;
-    }
-
-    /**
-     * Inserts a document into the collection
-     *
-     * @link http://php.net/manual/en/mongocollection.insert.php
-     * @param mixed $a
-     *            Array to save.
-     * @param array $options
-     *            Options for the save.
-     * @throws \MongoCursorException
-     * @return mixed
-     */
-    public function insert(array &$a, array $options = [])
-    {
-        $return = $this->mock->insert($a, $options);
-        if (!isset($a['_id']) || $a['_id'] === null) {
-            $a['_id'] = new \MongoId();
-        }
-        return $return;
-    }
-
-    /**
-     * String representation of this collection
-     *
-     * @return string
-     */
-    public function __toString()
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Returns this collections name
-     *
-     * @return string
-     */
-    public function getName()
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Drops this collection
-     *
-     * @return array
-     */
-    public function drop()
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Validates this collection
-     *
-     * @param boolean $scan_data
-     *            Only validate indices, not the base collection.
-     *
-     * @return array
-     */
-    public function validate($scan_data = false)
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Inserts multiple documents into this collection
-     *
-     * @param array $a
-     *            An array of arrays.
-     * @param array $options
-     *            Options for the inserts.
-     *
-     * @return mixed If "safe" is set, returns an associative array with the
-     *         status of the inserts ("ok")
-     *         and any error that may have occured ("err"). Otherwise, returns
-     *         TRUE if the batch insert
-     *         was successfully sent, FALSE otherwise.
-     */
-    public function batchInsert($a, $options = array())
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Update records based on a given criteria
-     *
-     * @param array $criteria
-     *            Description of the objects to update.
-     * @param array $newobj
-     *            The object with which to update the matching records.
-     * @param array $options
-     *            Options for update.
-     *
-     * @return boolean
-     */
-    public function update($criteria, $newobj, $options = array())
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Remove records from this collection
-     *
-     * @param array $criteria
-     *            Description of records to remove.
-     * @param array $options
-     *            Options for remove.
-     *
-     * @return mixed
-     */
-    public function remove($criteria = array(), $options = array())
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Querys this collection
-     *
-     * @param array $query
-     *            The fields for which to search
-     * @param array $fields
-     *            Fields of the results to return.
-     *            The array is in the format array('fieldname' => true,
-     *            'fieldname2' => true).
-     *            The _id field is always returned.
-     *
-     * @return MongoCursor
-     */
-    public function find($query = array(), $fields = array())
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Querys this collection, returning a single element
-     *
-     * As opposed to MongoCollection::find(), this method will return only the
-     * first
-     * result from the result set, and not a MongoCursor that can be iterated
-     * over.
-     *
-     * @param array $query
-     *            The fields for which to search
-     * @param array $fields
-     *            Fields of the results to return.
-     *            The array is in the format array('fieldname' => true,
-     *            'fieldname2' => true).
-     *            The _id field is always returned.
-     *
-     * @return array
-     */
-    public function findOne($query = array(), $fields = array(), $options = array())
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Creates an index on the given field(s), or does nothing if the index
-     * already exists
-     *
-     * @param array $keys
-     *            An array of fields by which to sort the index on.
-     *            Each element in the array has as key the field name,
-     *            and as value either 1 for ascending sort, or -1 for descending
-     *            sort.
-     * @param array $options
-     *            Options for the ensureIndex.
-     *
-     * @return boolean
-     */
-    public function ensureIndex($keys, $options = array())
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Deletes an index from this collection
-     *
-     * @param string|array $keys
-     *            Field or fields from which to delete the index.
-     *
-     * @return array
-     */
-    public function deleteIndex($keys)
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Delete all indices for this collection
-     *
-     * @return array
-     */
-    public function deleteIndexes()
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Returns an array of index names for this collection
-     *
-     * @return array
-     */
-    public function getIndexInfo()
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Counts the number of documents in this collection
-     *
-     * @param array $query
-     *            Associative array or object with fields to match.
-     * @param integer $limit
-     *            Specifies an upper limit to the number returned.
-     * @param integer $skip
-     *            Specifies a number of results to skip before starting the
-     *            count.
-     *
-     * @return integer
-     */
-    public function count($query = array(), $limit = null, $skip = null)
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Creates a database reference
-     *
-     * @param array $a
-     *            Object to which to create a reference.
-     *
-     * @return array
-     */
-    public function createDBRef($a)
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Fetches the document pointed to by a database reference
-     *
-     * @param array $ref
-     *            A database reference.
-     *
-     * @return array
-     */
-    public function getDBRef($ref)
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-
-    /**
-     * Performs an operation similar to SQL's GROUP BY command
-     *
-     * @param mixed $keys
-     *            Fields to group by. If an array or non-code object
-     *            is passed, it will be the key used to group results.
-     * @param array $initial
-     *            Initial value of the aggregation counter object.
-     * @param \MongoCode $reduce
-     *            A function that takes two arguments (the current
-     *            document and the aggregation to this point) and does the
-     *            aggregation.
-     * @param array $options
-     *            Optional parameters to the group command
-     *
-     * @return array
-     */
-    public function group($keys, $initial, $reduce, $options = array())
-    {
-        return $this->__call(__FUNCTION__, func_get_args());
-    }
-}
+$oldErrorLevel = error_reporting();
+error_reporting($oldErrorLevel & ~E_STRICT);
+include '_MongoCollectionMockProxy.php';
+error_reporting($oldErrorLevel);
\ No newline at end of file
diff --git a/tests/TestAsset/_MongoCollectionMockProxy.php b/tests/TestAsset/_MongoCollectionMockProxy.php
new file mode 100644
index 0000000..6d0fad4
--- /dev/null
+++ b/tests/TestAsset/_MongoCollectionMockProxy.php
@@ -0,0 +1,373 @@
+<?php
+/**
+ * MongoDB matryoshka wrapper
+ *
+ * @link        https://github.com/matryoshka-model/mongo-wrapper
+ * @copyright   Copyright (c) 2015, Ripa Club
+ * @license     http://opensource.org/licenses/BSD-2-Clause Simplified BSD License
+ */
+namespace MatryoshkaModelWrapperMongoTest\TestAsset;
+/**
+ * Class MongoCollectionMockProxy
+ *
+ * Proxy for \MongoCollection's mock in order to simulate the special behavior of insert() and save().
+ *
+ * MongoCollection::insert() and save() first parameter report the following specifications:
+ * if the parameter does not have an _id key or property, a new MongoId instance will be created and assigned to it.
+ * This special behavior does not mean that the parameter is passed by reference.
+ *
+ * The behavior can be simulated using parameter passed by reference but PHPUnit mock implementation doesn't allow that.
+ * MongoCollectionMockProxy bypasses the issue changing the original method signature,
+ * proxing the method call to the mock and finally adding the _id.
+ *
+ * NOTE: E_STRICT error reporting must be disabled due to incompatibile method signature with the parent class
+ *
+ * MongoCollection skeleton class by {@link https://github.com/localgod/PeclMongoPhpDoc}
+ */
+class MongoCollectionMockProxy extends \MongoCollection
+{
+    protected $mock;
+
+    /**
+     * Ctor
+     *
+     * @param
+     */
+    public function __construct()
+    {
+        //won't call parent::__construct
+    }
+
+    public function __MongoCollectionMockProxy__setMock($mock)
+    {
+        $this->mock = $mock;
+    }
+
+    public function __set($name, $value)
+    {
+        return $this->mock->{$name} = $value;
+    }
+
+    public function __get($name)
+    {
+        return $this->mock->{$name};
+    }
+
+    public function __call($method, array $params)
+    {
+        if (count($params) > 0) {
+            return call_user_func_array([$this->mock, $method], $params);
+        }
+        return call_user_func([$this->mock, $method]);
+    }
+
+    /**
+     * Saves an object to this collection
+     *
+     * @link http://www.php.net/manual/en/mongocollection.save.php
+     * @param mixed $a
+     *            Array to save.
+     * @param array $options
+     *            Options for the save.
+     * @throws \MongoCursorException
+     * @return mixed
+     */
+    public function save(array &$a, array $options = [])
+    {
+        $return = $this->mock->save($a, $options);
+        if (!isset($a['_id']) || $a['_id'] === null) {
+            $a['_id'] = new \MongoId();
+        }
+        return $return;
+    }
+
+    /**
+     * Inserts a document into the collection
+     *
+     * @link http://php.net/manual/en/mongocollection.insert.php
+     * @param mixed $a
+     *            Array to save.
+     * @param array $options
+     *            Options for the save.
+     * @throws \MongoCursorException
+     * @return mixed
+     */
+    public function insert(array &$a, array $options = [])
+    {
+        $return = $this->mock->insert($a, $options);
+        if (!isset($a['_id']) || $a['_id'] === null) {
+            $a['_id'] = new \MongoId();
+        }
+        return $return;
+    }
+
+    /**
+     * String representation of this collection
+     *
+     * @return string
+     */
+    public function __toString()
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Returns this collections name
+     *
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Drops this collection
+     *
+     * @return array
+     */
+    public function drop()
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Validates this collection
+     *
+     * @param boolean $scan_data
+     *            Only validate indices, not the base collection.
+     *
+     * @return array
+     */
+    public function validate($scan_data = false)
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Inserts multiple documents into this collection
+     *
+     * @param array $a
+     *            An array of arrays.
+     * @param array $options
+     *            Options for the inserts.
+     *
+     * @return mixed If "safe" is set, returns an associative array with the
+     *         status of the inserts ("ok")
+     *         and any error that may have occured ("err"). Otherwise, returns
+     *         TRUE if the batch insert
+     *         was successfully sent, FALSE otherwise.
+     */
+    public function batchInsert($a, $options = array())
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Update records based on a given criteria
+     *
+     * @param array $criteria
+     *            Description of the objects to update.
+     * @param array $newobj
+     *            The object with which to update the matching records.
+     * @param array $options
+     *            Options for update.
+     *
+     * @return boolean
+     */
+    public function update($criteria, $newobj, $options = array())
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Remove records from this collection
+     *
+     * @param array $criteria
+     *            Description of records to remove.
+     * @param array $options
+     *            Options for remove.
+     *
+     * @return mixed
+     */
+    public function remove($criteria = array(), $options = array())
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Querys this collection
+     *
+     * @param array $query
+     *            The fields for which to search
+     * @param array $fields
+     *            Fields of the results to return.
+     *            The array is in the format array('fieldname' => true,
+     *            'fieldname2' => true).
+     *            The _id field is always returned.
+     *
+     * @return MongoCursor
+     */
+    public function find($query = array(), $fields = array())
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Querys this collection, returning a single element
+     *
+     * As opposed to MongoCollection::find(), this method will return only the
+     * first
+     * result from the result set, and not a MongoCursor that can be iterated
+     * over.
+     *
+     * @param array $query
+     *            The fields for which to search
+     * @param array $fields
+     *            Fields of the results to return.
+     *            The array is in the format array('fieldname' => true,
+     *            'fieldname2' => true).
+     *            The _id field is always returned.
+     *
+     * @return array
+     */
+    public function findOne($query = array(), $fields = array(), $options = array())
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Creates an index on the given field(s), or does nothing if the index
+     * already exists
+     *
+     * @param array $keys
+     *            An array of fields by which to sort the index on.
+     *            Each element in the array has as key the field name,
+     *            and as value either 1 for ascending sort, or -1 for descending
+     *            sort.
+     * @param array $options
+     *            Options for the ensureIndex.
+     *
+     * @return boolean
+     */
+    public function ensureIndex($keys, $options = array())
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Deletes an index from this collection
+     *
+     * @param string|array $keys
+     *            Field or fields from which to delete the index.
+     *
+     * @return array
+     */
+    public function deleteIndex($keys)
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Delete all indices for this collection
+     *
+     * @return array
+     */
+    public function deleteIndexes()
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Returns an array of index names for this collection
+     *
+     * @return array
+     */
+    public function getIndexInfo()
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Counts the number of documents in this collection
+     *
+     * @param array $query
+     *            Associative array or object with fields to match.
+     * @param integer $limit
+     *            Specifies an upper limit to the number returned.
+     * @param integer $skip
+     *            Specifies a number of results to skip before starting the
+     *            count.
+     *
+     * @return integer
+     */
+    public function count($query = array(), $limit = null, $skip = null)
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Creates a database reference
+     *
+     * @param array $a
+     *            Object to which to create a reference.
+     *
+     * @return array
+     */
+    public function createDBRef($a)
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Fetches the document pointed to by a database reference
+     *
+     * @param array $ref
+     *            A database reference.
+     *
+     * @return array
+     */
+    public function getDBRef($ref)
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * Performs an operation similar to SQL's GROUP BY command
+     *
+     * @param mixed $keys
+     *            Fields to group by. If an array or non-code object
+     *            is passed, it will be the key used to group results.
+     * @param array $initial
+     *            Initial value of the aggregation counter object.
+     * @param \MongoCode $reduce
+     *            A function that takes two arguments (the current
+     *            document and the aggregation to this point) and does the
+     *            aggregation.
+     * @param array $options
+     *            Optional parameters to the group command
+     *
+     * @return array
+     */
+    public function group($keys, $initial, $reduce, $options = array())
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+
+    /**
+     * @param array $query
+     *              The query criteria to search for.
+     * @param array $update
+     *              The update criteria.
+     * @param array $fields
+     *              Optionally only return these fields.
+     * @param array $options
+     *              An array of options to apply, such as remove the match document from the DB and return it.
+     *
+     * @return array Returns the original document, or the modified document when new is set
+     */
+    public function findAndModify($query, $update = array(), $fields = array(), $options = array())
+    {
+        return $this->__call(__FUNCTION__, func_get_args());
+    }
+}