PhpSpreadsheet/tests/data/Calculation/TextData/UPPER.php

<?php

return [
    [
        'AbCdEfGhI',
        'ABCDEFGHI',
    ],
    [
        'mark baker',
        'MARK BAKER',
    ],
    [
        true,
        'TRUE',
    ],
    [
        false,
        'FALSE',
    ],
];