Google\Spreadsheet\Spreadsheet::addWorksheet PHP Method

    public function addWorksheet($title, $rowCount = 100, $colCount = 10)
    {
        $entry = new \SimpleXMLElement("\n            <entry\n                xmlns=\"http://www.w3.org/2005/Atom\"\n                xmlns:gs=\"http://schemas.google.com/spreadsheets/2006\">\n            </entry>\n        ");
        $entry->title = $title;
        $entry->addChild("xmlns:gs:rowCount", (int) $rowCount);
        $entry->addChild("xmlns:gs:colCount", (int) $colCount);
        $response = ServiceRequestFactory::getInstance()->post($this->getWorksheetsFeedUrl(), $entry->asXML());
        return new Worksheet(new \SimpleXMLElement($response));
    }

 public function testAddWorksheet()
 {
     $this->setServiceRequest('worksheet.xml');
     $xml = file_get_contents(__DIR__ . '/xml/spreadsheet.xml');
     $spreadsheet = new Spreadsheet(new SimpleXMLElement($xml));
     $this->assertTrue($spreadsheet->addWorksheet('Sheet 3') instanceof Worksheet);
 }