Insertion sort [algorithm] [problem at: https://www.hackerrank.com/challenges/insertionsort2]

insertion_sort.php

<?php

/**
 * Insertion sort
 *
 * @param array $input
 * @return array
 */
function insertionSort(array $input)
{
    // get count of items
    $itemsCount = count($input);

    // process items
    for ($i = 0; $i < $itemsCount; $i++) {

        for($j = $i; $j >= 0; $j--) {
            if (isset($input[$j - 1]) && $input[$j] < $input[$j - 1]) {
                // swap values
                list($input[$j], $input[$j - 1]) = [$input[$j - 1], $input[$j]];
            }
        }
    }

    return $input;
}

// tests
$testCases = [
    [
        'input' => [6, 5, 1, 3, 8, 4, 7, 9, 2],
        'expect' => '1 2 3 4 5 6 7 8 9'
    ],
    [
        'input' => [2, 0, -1],
        'expect' => '-1 0 2'
    ],
    [
        'input' => [2, 0, 1, 0],
        'expect' => '0 0 1 2'
    ],
    [
        'input' => [2, 0, 1, 0],
        'expect' => '0 0 1 2'
    ],
    [
        'input' => [1, 0, 0, 4],
        'expect' => '0 0 1 4'
    ],
    [
        'input' => [3, 2, 1, 0],
        'expect' => '0 1 2 3'
    ],
    [
        'input' => [3, 2, 1, 0, 4],
        'expect' => '0 1 2 3 4'
    ],
    [
        'input' => [0, 1, -1, 5, -2],
        'expect' => '-2 -1 0 1 5'
    ],
    [
        'input' => [5, 8, 0, -1, 0, 9, 5, -2],
        'expect' => '-2 -1 0 0 5 5 8 9'
    ],
];

foreach ($testCases as $case) {
    $result = implode(' ', insertionSort($case['input']));

    if ($case['expect'] == $result) {
        echo '<span style="color:green">passed:</span> ' . $case['expect'] . ' == ' . $result;
    }
    else {
        echo '<span style="color:red">failed:</span> ' . $case['expect'] . ' <>' . $result;
    }

    echo '<br />';
}