LayoutTests/js/sequence-iterator-protocol-2.html

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <script src="../resources/js-test-pre.js"></script>
    </head>
    <body>
        <pre id='console'></pre>
        <canvas></canvas>

        <script>
            "use strict";

            const log = console.log.bind(console);
            const canvas = document.querySelector("canvas");
            const ctx = canvas.getContext("2d");

            let callCount = 0;
            function makeValue(x) {
                return {
                    valueOf() { ++callCount; return x; }
                };
            }

            let array = [makeValue(1), makeValue(2), makeValue(3)];
            ctx.setLineDash(array);
            let a = ctx.getLineDash();
            log("Using an array but with objects with valueOf()");
            log(a);

            ctx.setLineDash([1,2,3]);
            let b = ctx.getLineDash();
            log(b);

            if (a.toString() !== b.toString())
                throw new Error("Bad result. They should be equal.");

            log(`callCount: ${callCount}`);
            if (callCount !== 3)
                throw new Error("Bad result. callCount should be 3.");


            let iter = [][Symbol.iterator]();
            let iterProto = Object.getPrototypeOf(iter);
            let oldNext = iterProto.next;

            callCount = 0;
            function hackedNext() {
                ++callCount;

                let val = oldNext.call(this);
                if ("value" in val) {
                    val.value++;
                }
                return val;
            }
            const obj = {
                valueOf: function() {
                    iterProto.next = hackedNext;
                    return 2;
                }
            };
            array = [1, obj, 3];
            ctx.setLineDash(array);
            b = ctx.getLineDash();
            log(`${b}`);

            iterProto.next = oldNext;
            ctx.setLineDash([1,2,3]);
            a = ctx.getLineDash();
            log(a);
            if (a.toString() !== b.toString())
                throw new Error("Bad result. They should be equal.");

            log(`callCount: ${callCount}`);
            if (callCount !== 0)
                throw new Error("Bad result. callCount should be 0.");

        </script>

        <script src="../resources/js-test-post.js"></script>

    </body>
</html>