PhpOffice\PhpPresentation\PresentationProperties::getThumbnailPath PHP Method

    public function getThumbnailPath()
    {
        return $this->thumbnail;
    }

 public function testThumbnail()
 {
     $imagePath = PHPPRESENTATION_TESTS_BASE_DIR . DIRECTORY_SEPARATOR . 'resources' . DIRECTORY_SEPARATOR . 'images' . DIRECTORY_SEPARATOR . 'PhpPresentationLogo.png';
     $object = new PresentationProperties();
     $this->assertNull($object->getThumbnailPath());
     $this->assertInstanceOf('PhpOffice\\PhpPresentation\\PresentationProperties', $object->setThumbnailPath('AAAA'));
     $this->assertNull($object->getThumbnailPath());
     $this->assertInstanceOf('PhpOffice\\PhpPresentation\\PresentationProperties', $object->setThumbnailPath());
     $this->assertNull($object->getThumbnailPath());
     $this->assertInstanceOf('PhpOffice\\PhpPresentation\\PresentationProperties', $object->setThumbnailPath($imagePath));
     $this->assertEquals($imagePath, $object->getThumbnailPath());
     $this->assertInstanceOf('PhpOffice\\PhpPresentation\\PresentationProperties', $object->setThumbnailPath());
     $this->assertEquals($imagePath, $object->getThumbnailPath());
 }