appendChild(y);
        parent.appendChild(z);
        child.after(v, x);
        var expected = innerHTML + '<v></v><x></x><y></y><z></z>';
        assert_equals(parent.innerHTML, expected);
    }, nodeName + '.after() with some siblings of child as arguments; no changes in tree.');

    test(function() {
        var parent = document.createElement('div');
        var x = document.createElement('x');
        var y = document.createElement('y');
        parent.appendChild(child);
        parent.appendChild(