Testing uploaded files

I'm using Laravel 5.2 with a small project and I got stucked with testing a file uploading feature. Basically, I'd to upload a pdf file, which I want to move to a specific folder on server and process it with a queue.

When I'm testing this feature, I always got the following exception:

1) UploadPayslipTest::an_administrator_can_upload_a_pdf_for_processing
Symfony\Component\HttpFoundation\File\Exception\FileException: The file "payslip.pdf" was not uploaded due to an unknown error.

In my test I'm using the following snippet:

protected function prepareFileUpload($path, $filename = 'payslip.pdf')
    {
        $this->assertFileExists($path);

        $finfo = finfo_open(FILEINFO_MIME_TYPE);

        $mime = finfo_file($finfo, $path);

        return new Symfony\Component\HttpFoundation\File\UploadedFile($path, $filename, $mime, null, null, true);
    } 

If i check the returned object, I got something like this:

Symfony\Component\HttpFoundation\File\UploadedFile {#631
  -test: true
  -originalName: "payslip.pdf"
  -mimeType: "application/pdf"
  -size: null
  -error: 0
  path: "/home/jpapp/Code/storage/../tests/files"
  filename: "payslip.pdf"
  basename: "payslip.pdf"
  pathname: "/home/jpapp/Code/storage/../tests/files/payslip.pdf"
  extension: "pdf"
  realPath: "/home/jpapp/Code/tests/files/payslip.pdf"
  aTime: 2016-02-29 21:04:13
  mTime: 2016-02-29 20:59:53
  cTime: 2016-02-29 21:02:31
  inode: 4341065
  size: 5797
  perms: 0100664
  owner: 1000
  group: 1000
  type: "file"
  writable: true
  readable: true
  executable: false
  file: true
  dir: false
  link: false
}

Which is fine. The next call is:

$response = $this->call('POST', '/admin/payslips/store', $parameters, [], [
            'payslip' => $payslip
        ]);

If I dd the uploaded file in the given controller method I get the following:

Illuminate\Http\UploadedFile {#692
  -test: false
  -originalName: "payslip.pdf"
  -mimeType: "application/pdf"
  -size: null
  -error: 0
  path: "/home/jpapp/Code/storage/../tests/files"
  filename: "payslip.pdf"
  basename: "payslip.pdf"
  pathname: "/home/jpapp/Code/storage/../tests/files/payslip.pdf"
  extension: "pdf"
  realPath: "/home/jpapp/Code/tests/files/payslip.pdf"
  aTime: 2016-02-29 21:04:13
  mTime: 2016-02-29 20:59:53
  cTime: 2016-02-29 21:02:31
  inode: 4341065
  size: 5797
  perms: 0100664
  owner: 1000
  group: 1000
  type: "file"
  writable: true
  readable: true
  executable: false
  file: true
  dir: false
  link: false
}

Since it's no longer in test (please see the private property above), I can't call the move method on this file, 'cause I get the above mentioned exception.

Any idea how to test it properly?