diff --git a/tests/FilesystemTests.php b/tests/FilesystemTests.php
new file mode 100644
index 0000000..a0e66ac
--- /dev/null
+++ b/tests/FilesystemTests.php
@@ -0,0 +1,171 @@
+<?php
+
+class FileMock
+{
+	protected $return = true;
+
+	public function __construct($return)
+	{
+		$this->return = $return;
+	}
+
+	public $file = array(
+		'_id' => 'some_id',
+	);
+
+	public function write()
+	{
+		return $this->return;
+	}
+}
+
+class FilesystemTests extends PHPUnit_Framework_TestCase
+{
+	public function testStore()
+	{
+		$id = new MongoId('09ecu0q9fh2h3');
+
+		$mock = $this->getMockBuilder('MongoGridFS')
+			->disableOriginalConstructor()
+			->setMethods(array('put'))
+			->getMock();
+
+		$mock->expects($this->once())
+			->method('put')
+			->with('filename.json', array('downloads' => 0))
+			->will($this->returnValue($id));
+
+		$fs = new Monga\Filesystem($mock);
+
+		$result = $fs->store('filename.json', array('downloads' => 0));
+		$this->assertEquals($id, $result);
+	}
+
+	public function testStoreBytes()
+	{
+		$id = new MongoId('09ecu0q9fh2h3');
+
+		$mock = $this->getMockBuilder('MongoGridFS')
+			->disableOriginalConstructor()
+			->setMethods(array('storeBytes'))
+			->getMock();
+
+		$mock->expects($this->once())
+			->method('storeBytes')
+			->with('filename.json', array('downloads' => 0), array())
+			->will($this->returnValue($id));
+
+		$fs = new Monga\Filesystem($mock);
+
+		$result = $fs->storeBytes('filename.json', array('downloads' => 0));
+		$this->assertEquals($id, $result);
+	}
+
+	public function testStoreUpload()
+	{
+		$id = new MongoId('09ecu0q9fh2h3');
+
+		$mock = $this->getMockBuilder('MongoGridFS')
+			->disableOriginalConstructor()
+			->setMethods(array('storeUpload'))
+			->getMock();
+
+		$mock->expects($this->once())
+			->method('storeUpload')
+			->with('filename.json', array('downloads' => 0))
+			->will($this->returnValue($id));
+
+		$fs = new Monga\Filesystem($mock);
+
+		$result = $fs->storeUpload('filename.json', array('downloads' => 0));
+		$this->assertEquals($id, $result);
+	}
+
+	public function testExtractFailing()
+	{
+		$mock = $this->getMockBuilder('MongoGridFS')
+			->disableOriginalConstructor()
+			->setMethods(array('extract', 'findOne', 'remove'))
+			->getMock();
+
+		$fileMock = $this->getMockBuilder('MongoGridFile')
+			->disableOriginalConstructor()
+			->setMethods(array('write'))
+			->getMock();
+
+		$mock->expects($this->once())
+			->method('findOne')
+			->with('filename.json')
+			->will($this->returnValue(new FileMock(false)));
+
+
+		$fs = new Monga\Filesystem($mock);
+
+		$this->assertFalse($fs->extract('filename.json'));
+	}
+
+	public function testExtract()
+	{
+		$mock = $this->getMockBuilder('MongoGridFS')
+			->disableOriginalConstructor()
+			->setMethods(array('extract', 'findOne', 'remove'))
+			->getMock();
+
+		$fileMock = $this->getMockBuilder('MongoGridFile')
+			->disableOriginalConstructor()
+			->setMethods(array('write'))
+			->getMock();
+
+		$mock->expects($this->once())
+			->method('findOne')
+			->with('filename.json')
+			->will($this->returnValue(new FileMock(true)));
+
+		$mock->expects($this->once())
+			->method('remove')
+			->with(array('_id' => 'some_id'))
+			->will($this->returnValue(true));
+
+		$fs = new Monga\Filesystem($mock);
+
+		$this->assertTrue($fs->extract('filename.json'));
+	}
+
+	public function testStoreFile()
+	{
+		$id = new MongoId('09ecu0q9fh2h3');
+
+		$mock = $this->getMockBuilder('MongoGridFS')
+			->disableOriginalConstructor()
+			->setMethods(array('storeFile'))
+			->getMock();
+
+		$mock->expects($this->once())
+			->method('storeFile')
+			->with('filename.json', array('downloads' => 0), array())
+			->will($this->returnValue($id));
+
+		$fs = new Monga\Filesystem($mock);
+
+		$result = $fs->storeFile('filename.json', array('downloads' => 0));
+		$this->assertEquals($id, $result);
+	}
+
+	public function testFindOne()
+	{
+		$mock = $this->getMockBuilder('MongoGridFS')
+			->disableOriginalConstructor()
+			->setMethods(array('findOne'))
+			->getMock();
+
+		$mock->expects($this->once())
+			->method('findOne')
+			->with(array('key' => 'value'))
+			->will($this->returnValue('_dummy_'));
+
+		$fs = new Monga\Filesystem($mock);
+
+		$result = $fs->findOne(array('key' => 'value'));
+		$this->assertEquals('_dummy_', $result);
+	}
+}
\ No newline at end of file