<!DOCTYPE html>
<html>
    <head>
        <style>
            body {
                overflow: hidden;
                margin: 0;
            }

            #container {
                width: 300px;
                height: 300px;
                display: inline-block;
                overflow-x: hidden;
                overflow-y: auto;
                scroll-snap-type: y mandatory;
            }

            .child {
                height: 300px;
                width: 300px;
                float: left;
                scroll-snap-align: start;
            }
        </style>
        <script>
        let write = s => output.innerHTML += s + "<br>";
        function run() {
            container.scrollTop = 300;
            write(`The scroll position is: ${container.scrollTop}`);
            if (!window.eventSender || !window.testRunner)
                return;

            testRunner.dumpAsText();
            testRunner.waitUntilDone();
            eventSender.monitorWheelEvents();
            internals.setPlatformMomentumScrollingPredictionEnabled(false);
            eventSender.mouseMoveTo(container.offsetLeft + container.clientWidth / 2, container.offsetTop + container.clientHeight / 2);

            write("Scrolling without momentum to the same position several times")
            for (let i = 0; i < 10; i++) {
                eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, "began", "none");
                eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 1, "changed", "none");
                eventSender.mouseScrollByWithWheelAndMomentumPhases(0, -1, "changed", "none");
                eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, "changed", "none");
                eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, "ended", "none");
            }

            setTimeout(() => {
                eventSender.callAfterScrollingCompletes(() => {
                    write(`The scroll position is now: ${container.scrollTop}`);
                    testRunner.notifyDone();
                });
            }, 0);
        }
        </script>
    </head>
    <body onload=run()>
        <p>To manually test, scroll so the green box exactly fills the container, and let go.</p>
        <p>The scroll position should not jump to the top.</p>
        <div id="container">
            <div style="background-color: red;" class="child"></div>
            <div style="background-color: green;" class="child"></div>
        </div>
        <div id="output"></div>
    </body>
</html>