Selection sort tests

// Translation of Mike Taylor's selection sort unit tests from Ruby to JavaScript.
// http://reprog.wordpress.com/2010/05/20/what-does-it-take-to-test-a-sorting-routine/

function arraysAreEqual(arr1, arr2) {
    if (arr1.length !== arr2.length) {
        return false;
    } else {
        for (var i = 0; i < arr1.length; i++) {
            if (arr1[i] !== arr2[i]) {
                return false;
            }
        }
    }

    return true;
}

function numericComp(a, b) {
    return (a < b ? -1 :
            a > b ?  1 : 0);
}

var output = (
    console !== undefined && console.hasOwnProperty("log") ?
    console.log :
    function(msg) { alert(msg); }
);

var tests = [
    [],
    [0],
    [0, 0],
    [0, 0, 0],
    [0, 1],
    [1, 0],
    [0, 1, 2],
    [0, 2, 1],
    [1, 0, 2],
    [1, 2, 0],
    [2, 0, 1],
    [2, 1, 0],
    [0, 1, 1],
    [1, 0, 1],
    [1, 1, 0],
    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
    [10, 9, 8, 7, 6, 5, 4, 3, 2, 1],
    [42, 9, 17, 54, 602, -3, 54, 999, -11],
    [-11, -3, 9, 17, 42, 54, 54, 602, 999],
    [6, -Infinity, 7, -Number.MAX_VALUE, -3, 0, Infinity, 1, Number.MAX_VALUE, -26]
];

var random_tests = [];
for (var i = 0; i < 10; i++) {
    var a = [];
    var size = Math.floor(Math.random() * 100);

    for (var j = 0; j < size; j++) {
        a.push(Math.random() * 1000000-500000);
    }

    random_tests.push(a);
}

var ntests = 0;
var nok = 0;
var all_tests = tests.concat(random_tests);

for (var i = 0; i < all_tests.length; i++) {
    var a = all_tests[i];
    var copy = a.slice();
    selectionSort(copy);

    if (arraysAreEqual(copy, a.sort(numericComp))) {
        nok += 1;
    } else {
        output("failed test " + i + ": [" + a.join(' ') + "] -> [" + copy.join(' ') + "]");
    }

    ntests += 1;
}
output("passed " + nok + " of " + ntests + " tests (" + 100*nok/ntests + "%)");