How to mock file system with Laravel and vfsStream? [Laravel 5.1]

I have request like this:

$path = storage_path('testing/unnamed.png');
        $original_name = 'unnamed';
        $mime_type = 'image/png';
        $size = 2192;
        $error = null;
        $test = true;

        $file = new UploadedFile($path, $original_name, $mime_type, $size, $error, $test);



        $response = $this->call('POST', 'games', [
            'name' => 'TEST321',
            'category' => 'test',], [], ['picture' => $file], []);

And insted of storing image how can I mock file system?

Also this don't pass laravel mime validation mimes:jpeg,bmp,png... Anyone know how to fix it?

via Chebli Mohamed