public function testGetFilename()
 {
     $asset = $this->getAsset();
     $asset->expects($this->once())->method('getFilename')->willReturn('test');
     $asset->expects($this->once())->method('getExtension')->willReturn('pdf');
     $thumbnail = new PdfThumbnail($asset);
     $this->assertEquals('test.thumb', $thumbnail->getFilename());
 }