<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>DOM getters should perform type checks</title>
    <script src="../../resources/testharness.js"></script>
    <script src="../../resources/testharnessreport.js"></script>
</head>
<body>
<script>
    var div = document.createElement("div");
    var getter = Object.getOwnPropertyDescriptor(Element.prototype, "scrollTop").get;

    test(() => {
        assert_equals(typeof getter, "function");
    }, "DOM getter should be a function");

    test(() => {
        assert_throws(new TypeError(), () => { getter(); }, "DOM getter throws an error with undefined");
        assert_throws(new TypeError(), () => { getter.call(null); }, "DOM getter throws an error with null");
        assert_throws(new TypeError(), () => { getter.call({}); }, "DOM getter throws an error with unrelated object");
        assert_throws(new TypeError(), () => { getter.call(document.createText("Hello")); }, "DOM getter throws an error with unrelated DOM object");
    }, "DOM getter throws an error with unrelated values");

    test(() => {
        assert_equals(typeof getter.call(div), "number");
    }, "DOM getter works with element object");

    test(() => {
        var object = {
        };
        Object.defineProperty(object, "scrollTop", {
            get: getter
        });
        assert_throws(new TypeError(), () => { object.scrollTop; });
    }, "DOM getter access throws an error with unrelated object");

    test(() => {
        var object = {
            __proto__: Element.prototype
        };
        assert_throws(new TypeError(), () => { object.scrollTop; });
    }, "DOM getter access through Element.prototype throws an error with unrelated object");
</script>
</body>