fullscreen/api/element-request-fullscreen-active-document.html

<!DOCTYPE html>
<title>
    Element#requestFullscreen() when the document is not the active document
</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="log"></div>
<iframe allowfullscreen></iframe>
<script>
    promise_test(async (t) => {
        const iframe = document.querySelector("iframe");
        const typeErrorConstructor = iframe.contentWindow.TypeError;
        const documentBeforeNav = iframe.contentDocument;

        documentBeforeNav.onfullscreenchange = t.unreached_func(
            "fullscreenchange event"
        );
        documentBeforeNav.onfullscreenerror = t.unreached_func(
            "fullscreenerror event"
        );

        await new Promise((r) => {
            iframe.src = "/common/blank.html";
            iframe.onload = r;
        });

        await promise_rejects_js(
            t,
            typeErrorConstructor,
            documentBeforeNav.documentElement.requestFullscreen()
        );

        // Per spec the fullscreenerror event should be fired at the next animation
        // frame, but at least Gecko and WebKit will instead effectively do "queue a
        // task to fire ...". Use both rAF and setTimeout to fail even if the timing
        // of the (unexpected) event isn't as expected.
        await new Promise((resolve) => {
            requestAnimationFrame(() => {
                t.step_timeout(resolve);
            });
        });
    });
</script>