track-selection-task-order.html

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This WPT test may be referenced by the following Test IDs:
- /html/semantics/embedded-content/media-elements/track/track-element/track-selection-task-order.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<title>HTMLTrackElement Text Track Selection Task Order</title>

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

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

<script>

/**

 * This test is used to ensure that we queue 'honor user preferences for automatic

 * text track selection' as a macro task, not a micro task. In this test, we

 * trigger a media event before queuing a text track selection task, and check

 * the text track's mode to know whether the text track selection runs after the

 * task for media event.

*/

async_test(function(t) {

    let video = document.createElement("video");

    video.play();

    video.onplay = t.step_func(startedPlay);

    // When we create a text track element, it queue a task to run automatic

    // text track selection later.

    let track = document.createElement("track");

    track.default = true;

    video.appendChild(track);

    assert_equals(track.track.mode, "disabled", "Text track's mode is disabled by default.");

    function startedPlay() {

        assert_equals(track.track.mode, "disabled", "Text track selection hasn't started yet.");

        track.onerror = t.step_func_done(trackError);

    function trackError() {

        assert_equals(track.track.mode, "showing", "Text track selection modified track's mode.");

        t.done();

});

</script>