serenity/Tests/LibWeb/Text/input/clipboard.html

<button id="button"></button>
<script src="include.js"></script>
<script type="text/javascript">
    function writeText(onComplete) {
        navigator.clipboard.writeText("Well hello friends :^)").then(
            () => {
                println("Success");
                onComplete();
            },
            () => {
                println("Failure");
                onComplete();
            }
        );
    }

    asyncTest((done) => {
        writeText(() => {
            const button = document.getElementById("button");
            internals.dispatchUserActivatedEvent(button, new Event("mousedown"));
            button.dispatchEvent(new Event("click"));

            writeText(done);
        });
    });
</script>