LayoutTests/js/script-tests/for-in-modify-in-loop.js

description("Check for ... in will properly enumerate elements added or deleted during the loop");

function haveSameProperties(a, b) {
    var p;

    for (p in a) {
        if (!b.hasOwnProperty(p))
            return false;
    }

    for (p in b) {
        if (!a.hasOwnProperty(p))
            return false;
    }

    return true;
}

function each(o, callback) {
    var result = {};

    for (var property in o) {
        callback(property, o);
        if (result.hasOwnProperty(property))
            throw "Duplicate property \"" + property + "\" enumerated";
        result[property] = 1;
    }

    return result;
}

function testAdd()
{
    var obj = { a : "First" };
    obj["m"] = "Second";
    obj["z"] = "Third";

    var elementsToAdd = [ "c", "t", "k" ];
    var addIndex = 0;

    var result = {};

    return each(obj, function(p, o) {
        if (addIndex < elementsToAdd.length)
            o[elementsToAdd[addIndex++]] = "Added #" + addIndex;
    });
}

function testDelete()
{
    var obj = { a : "First" };
    obj["b"] = "Second";
    obj["c"] = "Third";
    obj["d"] = "Fourth";

    var elementsToDelete = [ "c" ];
    var deleteIndex = 0;

    return each(obj, function(p, o) {
        if (deleteIndex < elementsToDelete.length)
            delete o[elementsToDelete[deleteIndex++]];
   });
}

function testAddDelete()
{
    var obj = { a : "First", b : "Second", c : "Third", j : "Fourth", z : "Fifth", lastOne : "The End" };

    elementsToAdd = [ "d", "p" ];
    elementsToDelete = [ "z", "lastOne", "c" ];
    var loopIndex = 0;

    return each(obj, function(p, o) {
        if (loopIndex++ == 1) {
            for (var i = 0; i < elementsToAdd.length; i++)
                o[elementsToAdd[i]] = "Added #" + i;
            for (var i = 0; i < elementsToDelete.length; i++)
                delete o[elementsToDelete[i]];
        }
   });
}

shouldBeTrue("haveSameProperties(testAdd(), { a: 1, m : 1, z : 1 })");
shouldBeTrue("haveSameProperties(testDelete(), { a: 1, b : 1, d : 1 })");
shouldBeTrue("haveSameProperties(testAddDelete(), { a: 1, b : 1, j : 1 })");

for (var i = 0; i < 10000; i++) {
    if (!haveSameProperties(testAdd(), { a: 1, m : 1, z : 1 }))
        shouldBeTrue("haveSameProperties(testAdd(), { a: 1, m : 1, z : 1 })");

    if (!haveSameProperties(testDelete(), { a: 1, b : 1, d : 1 }))
        shouldBeTrue("haveSameProperties(testDelete(), { a: 1, b : 1, d : 1 })");

    if (!haveSameProperties(testAddDelete(), { a: 1, b : 1, j : 1 }))
        shouldBeTrue("haveSameProperties(testAddDelete(), { a: 1, b : 1, j : 1 })");
}