removeSheetByIndex(0); $worksheet = new Worksheet($mySpreadsheet, 'addedsheet'); self::assertSame(-1, $mySpreadsheet->getActiveSheetIndex()); $mySpreadsheet->addSheet($worksheet, $sheetNumber); self::assertSame('addedsheet', $mySpreadsheet->getActiveSheet()->getTitle()); $row = 1; $col = 1; $worksheet->getCell([$col, $row])->setValue('id_uti'); self::assertSame('id_uti', $worksheet->getCell([$col, $row])->getValue()); $mySpreadsheet->disconnectWorksheets(); } public static function providerSheetNumber(): array { return [ 'problem case' => [0], 'normal case' => [null], 'negative 1 (as if there were no sheets)' => [-1], 'diffeent negative number' => [-4], 'positive number' => [4], ]; } }