function testFreeze() {
    var arr = [];
    for (var i = 0; i < 20; i++)
        arr.push(i);
    for (var i = 0; i < 10; i++)
        arr.shift();
    Object.freeze(arr);
    assertEq(arr.length, 10);
    arr[0] = -1;
    assertEq(arr[0], 10);
}
testFreeze();
testFreeze();

function testCopyOnWrite() {
    var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];
    for (var i = 0; i < 5; i++)
        assertEq(arr.shift(), i + 1);
    assertEq(arr.toString(), "6,7,8,9");
}
testCopyOnWrite();
testCopyOnWrite();

function testNonWritableLength() {
    var arr = [];
    for (var i = 0; i < 20; i++)
        arr.push(i);
    Object.defineProperty(arr, "length", {writable: false, value: arr.length});
    var ex;
    try {
        arr.shift();
    } catch(e) {
        ex = e;
    }
    assertEq(ex instanceof TypeError, true);
    assertEq(arr.length, 20);
}
testNonWritableLength();
testNonWritableLength();