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

<?php

return [
    [
        'HELLO    ',
        'HELLO',
    ],
    [
        '    HELLO',
        'HELLO',
    ],
    [
        '   HELLO      ',
        'HELLO',
    ],
    [
        '	HELLO',
        '	HELLO',
    ],
    [
        'HELLO    WORLD',
        'HELLO WORLD',
    ],
    [
        true,
        'TRUE',
    ],
    [
        null,
        null,
    ],
];