endtoend-test-psl/tests/Psl/Iter/LastKeyTest.php

<?php

declare(strict_types=1);

namespace Psl\Tests\Iter;

use PHPUnit\Framework\TestCase;
use Psl\Iter;

class LastKeyTest extends TestCase
{
    /**
     * @dataProvider provideData
     */
    public function testLastKey($expected, iterable $iterable): void
    {
        $result = Iter\last_key($iterable);

        self::assertSame($expected, $result);
    }

    public function provideData(): iterable
    {
        yield [3, [1, 2, 3, 4]];
        yield [3, Iter\to_iterator([1, 2, 3, 4])];
        yield [3, Iter\range(1, 4)];
        yield [4, Iter\range(4, 8)];
        yield [null, []];
        yield [0, [null]];
        yield [1, [null, null]];
        yield [[1, 2], (fn () => yield [1, 2] => 'hello')()];
    }
}