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

<?php

return [
    [
        'ABCDE',
        'FGHIJ',
        'ABCDEFGHIJ',
    ],
    [
        1,
        2,
        3,
        '123',
    ],
    [
        'Boolean',
        '-',
        true,
        'Boolean-TRUE',
    ],
];