public function testGetSetDocument()
 {
     $expectedDocument = new IncomingDocument();
     $this->page->setDocument($expectedDocument);
     $this->assertEquals($expectedDocument, $this->page->getDocument());
     try {
         $this->page->setDocument($expectedDocument);
     } catch (\Exception $e) {
         $this->assertTrue($e instanceof \LogicException);
     }
 }
 /**
  * @param Page $page
  *
  * @return Document
  */
 public function addPage(Page $page)
 {
     $nextPageNumber = count($this->pages) + 1;
     $page->setPageNumber($nextPageNumber);
     $page->setDocument($this);
     $this->pages->set($nextPageNumber, $page);
     return $this;
 }