PhpSpreadsheet/tests/PhpSpreadsheetTests/Functional/FreezePaneTest.php

<?php

namespace PhpOffice\PhpSpreadsheetTests\Functional;

use PhpOffice\PhpSpreadsheet\Spreadsheet;

class FreezePaneTest extends AbstractFunctional
{
    public function providerFormats()
    {
        return [
            ['Xls'],
            ['Xlsx'],
        ];
    }

    /**
     * @dataProvider providerFormats
     *
     * @param string $format
     */
    public function testFreezePane($format)
    {
        $cellSplit = 'B4';
        $topLeftCell = 'E7';

        $spreadsheet = new Spreadsheet();
        $spreadsheet->getActiveSheet()->freezePane($cellSplit, $topLeftCell);

        $reloadedSpreadsheet = $this->writeAndReload($spreadsheet, $format);

        // Read written file
        $reloadedActive = $reloadedSpreadsheet->getActiveSheet();
        $actualCellSplit = $reloadedActive->getFreezePane();
        $actualTopLeftCell = $reloadedActive->getTopLeftCell();

        self::assertSame($cellSplit, $actualCellSplit, 'should be able to set freeze pane');
        self::assertSame($topLeftCell, $actualTopLeftCell, 'should be able to set the top left cell');
    }
}