/**
  *
  */
 public function testWrite()
 {
     $fileSystem = $this->getFileSystem();
     $fileSystem->shouldReceive('isWritable')->once()->with('/sessions')->andReturn(true);
     $fileSystem->shouldReceive('putContents')->once()->with('/sessions/123', serialize('data'));
     $file = new File($fileSystem, '/sessions');
     $file->write('123', 'data', 123);
 }