ray_equals(parent.childNodes, [x]);
    }, nodeName + '.append() with only one element as an argument, on a parent having no child.');

    test(function() {
        const parent = node.cloneNode();
        const child = document.createElement('test');
        parent.appendChild(child);
        parent.append(null);
        assert_equals(parent.childNodes[0], child);
        assert_equals(parent.childNodes[1].textContent, 'null');
    }, nodeName + '.append() with null as an argument, on a parent having a ch