preload-time-to-fetch.https.html

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /preload/preload-time-to-fetch.https.html - WPT Dashboard Interop Dashboard

<!doctype html>

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

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

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

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

<script src="/preload/resources/preload_helper.js"></script>

<body>

<script>

function test_preload_change(before, after, expected, label) {

    promise_test(async t => {

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

        link.rel = 'preload';

        t.add_cleanup(() => link.remove());

        const loadErrorOrTimeout = () => new Promise(resolve => {

            const timeoutMillis = 1000;

            link.addEventListener('load', () => resolve('load'));

            link.addEventListener('error', () => resolve('error'));

            t.step_timeout(() => resolve('timeout'), timeoutMillis);

});

        for (const attr in before)

            link.setAttribute(attr, before[attr]);

        document.head.appendChild(link);

        const result1 = await loadErrorOrTimeout();

        for (const attr in after) {

            if (attr in before && after[attr] === null)

                link.removeAttribute(attr);

            else

                link.setAttribute(attr, after[attr]);

        const result2 = await loadErrorOrTimeout();

        assert_array_equals([result1, result2], expected);

    }, label);

test_preload_change(

    {href: '/common/square.png?1', as: 'image'},

    {href: '/common/square.png?2'},

    ['load', 'load'],

    'Changing a preload href should trigger a fetch');

test_preload_change(

    {href: '/common/square.png?3', as: 'style'},

    {as: 'image'},

    ['load', 'load'],

    'Changing a preload "as" from a previously non-matching destination should trigger a fetch');

test_preload_change(

    {href: '/common/square.png?4', type: 'text/plain', as: 'image'},

    {type: 'image/png'},

    ['timeout', 'load'],

    'Changing a preload "type" (non-matching->matching) should trigger a fetch');

test_preload_change(

    {href: '/common/square.png?4', type: 'text/plain', as: 'image'},

    {type: null},

    ['timeout', 'load'],

    'Removing a preload non-matching "type" should trigger a fetch');

test_preload_change(

    {href: '/common/square.png?4', type: 'image/png', as: 'image'},

    {type: null},

    ['load', 'timeout'],

    'Removing a preload matching "type" should not trigger a fetch');

test_preload_change(

    {href: '/common/square.png?5', as: 'image', media: 'screen and (max-width: 10px)'},

    {media: 'screen and (max-width: 20000px)'},

    ['timeout', 'load'],

    'Changing a preload media attribute (non matching->matching) should trigger a fetch');

test_preload_change(

    {href: '/common/square.png?6', as: 'image', media: 'screen and (max-width: 10px)'},

    {media: 'screen and (max-width: 20px)'},

    ['timeout', 'timeout'],

    'Changing a preload media attribute (non matching->non matching) should not trigger a fetch');

test_preload_change(

    {href: '/common/square.png?7', as: 'image', media: 'screen and (max-width: 100000px)'},

    {media: 'screen and (max-width: 20000px)'},

    ['load', 'timeout'],

    'Changing a preload media attribute (matching->matching) should not trigger a new fetch');

test_preload_change(

    {href: '/common/square.png?8', as: 'image', media: 'screen and (max-width: 100000px)'},

    {media: null},

    ['load', 'timeout'],

    'Removing a matching preload media attribute should not trigger a new fetch');

test_preload_change(

    {href: '/common/square.png?9', as: 'image', media: 'screen and (max-width: 10px)'},

    {media: null},

    ['timeout', 'load'],

    'Removing a non-matching preload media attribute should trigger a new fetch');

</script>

</body>