Gc\Property\Model::isRequired PHP Method

    public function isRequired($value = null)
    {
        if ($value === null) {
            return $this->getData('required');
        }
        if ($value === true) {
            $this->setData('required', true);
        } else {
            $this->setData('required', false);
        }
        return $this;
    }

 /**
  * Test
  *
  * @return void
  */
 public function testSaveValue()
 {
     $documentModel = DocumentModel::fromArray(array('name' => 'DocumentTest', 'url_key' => 'document-test', 'status' => DocumentModel::STATUS_ENABLE, 'sort_order' => 1, 'show_in_nav' => true, 'user_id' => $this->user->getId(), 'document_type_id' => $this->documentType->getId(), 'view_id' => $this->view->getId(), 'layout_id' => $this->layout->getId(), 'parent_id' => 0));
     $documentModel->save();
     $this->object->setDocumentId($documentModel->getId());
     $this->assertTrue($this->object->saveValue());
     $this->object->isRequired(true);
     $this->assertFalse($this->object->saveValue());
 }