paint-timing-mixin.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:
- /paint-timing/paint-timing-mixin.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<head>

<title>Performance Paint Timing: Check that paintTime/presentationTime are available</title>

</head>

<body>

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

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

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

<script>

  setup({"hide_test_state": true});

  promise_test(async t => {

    assert_implements(window.PerformancePaintTiming, "Paint Timing isn't supported.");

    assert_implements("paintTime" in window.PerformancePaintTiming.prototype, "Paint Timing doesn't expose `paintTime`");

    await new Promise(r => window.addEventListener('load', r));

    await assertNoFirstContentfulPaint(t);

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

    img.src = 'resources/circles.png';

    document.body.append(img);

    const reference_time = performance.now();

    const performance_entry_promise = new Promise(resolve => {

        new PerformanceObserver(entries => {

            const [entry] = entries.getEntriesByName("first-contentful-paint");

            if (entry)

                resolve(entry);

        }).observe({type: "paint"});

});

    await new Promise(resolve => img.addEventListener("load", () => resolve()));

    const entry = await performance_entry_promise;

    assert_greater_than(entry.paintTime, reference_time);

    assert_greater_than(entry.presentationTime, entry.paintTime);

    assert_equals(entry.presentationTime, entry.startTime);

}, "Paint timing entries should expose paintTime and presentationTime");

</script>

</body>

</html>