nested-unload-timing.html

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This WPT test may be referenced by the following Test IDs:
- /navigation-timing/nested-unload-timing.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8" />

    <meta name="timeout" content="long">

    <title>Navigation Timing: unload event with nested contexts</title>

    <link rel="help" href="https://w3c.github.io/navigation-timing/"/>

    <script src="/common/utils.js"></script>

    <script src="/common/dispatcher/dispatcher.js"></script>

    <script src="/resources/testharness.js"></script>

    <script src="/resources/testharnessreport.js"></script>

</head>

<body>

<script>

    const dummyURL = () => `/navigation-timing/resources/blank_page_green.html?uid=${token()}`;

    promise_test(async t => {

        const mainWindowUnloadDuration = 100;

        const iframeUnloadDuration = 400;

/*

            We create 3 contexts: One for a popup window that will load a document and then later

            unload it, one for an iframe inside that popup window, that will unload with the parent

            document as well, and one for document the popup window will load in order to trigger

            those previous unload events.

            The iframe is going to busy-wait on unload for 400ms, and the unloading top-level

            document is going to busy-wait on unload for 100ms.

            We verify that the total unloadEvent duration measured at the final document is ~100 but

            less than 500ms - does not include the unload event duration from the iframe.

*/

        const popupContext = new RemoteContext(token());

        const iframeContext = new RemoteContext(token());

        const finalContext = new RemoteContext(token());

        const popup = window.open(remoteExecutorUrl(popupContext.context_id));

        t.add_cleanup(() => popup.close());

        const registerBusyWaitUnload = duration => window.addEventListener('unload', () => {

            const buffer = 3;

            const timeoutEnd = performance.now() + duration + buffer;

            while (timeoutEnd > performance.now()) {}

});

        await popupContext.execute_script(registerBusyWaitUnload, [mainWindowUnloadDuration]);

        const unloadIframe = iframeContext.execute_script(registerBusyWaitUnload, [iframeUnloadDuration]);

        const loadPopup = popupContext.execute_script(async iframeUid => {

            const iframe = document.createElement('iframe');

            iframe.src = `/common/dispatcher/remote-executor.html?uuid=${iframeUid}`;

            document.body.appendChild(iframe);

            await new Promise(resolve => iframe.addEventListener('load', resolve));

        }, [iframeContext.context_id]);

        await Promise.all([unloadIframe, loadPopup]);

        await popupContext.execute_script((uid) => location.href = `/common/dispatcher/remote-executor.html?uuid=${uid}`, [finalContext.context_id]);

        const navigationTimingEntry = await finalContext.execute_script(() => performance.getEntriesByType('navigation')[0].toJSON());

        const unloadDuration = navigationTimingEntry.unloadEventEnd - navigationTimingEntry.unloadEventStart;

        assert_greater_than_equal(unloadDuration, mainWindowUnloadDuration);

        assert_less_than(unloadDuration, mainWindowUnloadDuration + iframeUnloadDuration);

});

</script>

</body>