public function testCanKeepFinalId()
{
$document = $this->getDocument1();
$file = $this->getOutFile();
$pdf = new Pdf($document);
$this->assertInstanceOf('mikehaertl\\pdftk\\Pdf', $pdf->keepId('final'));
$this->assertTrue($pdf->saveAs($file));
$this->assertFileExists($file);
$tmpFile = (string) $pdf->getTmpFile();
$this->assertEquals("pdftk A='{$document}' output '{$tmpFile}' keep_final_id", (string) $pdf->getCommand());
}