test_webvtt_process_cues_exception.html

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<!doctype html>

<html>

<head>

  <meta charset="utf-8">

  <title>WebVTT should recover after an exception while processing cues</title>

  <script src="/tests/SimpleTest/SimpleTest.js"></script>

  <link rel="stylesheet" href="/tests/SimpleTest/test.css">

  <style>

    #overlay {

      position: relative;

      width: 320px;

      height: 180px;

  </style>

</head>

<body>

<div id="overlay"></div>

<script>

"use strict";

add_task(function test_process_cues_recovers_after_exception() {

  const { WebVTT } = SpecialPowers.ChromeUtils.importESModule(

    "resource://gre/modules/vtt.sys.mjs"

);

  let thrownError;

  try {

    WebVTT.processCues(window, null, null, null);

  } catch (error) {

    thrownError = error;

  ok(thrownError, "Processing cues with an invalid overlay should throw");

is(

    WebVTT.isProcessingCues,

    false,

    "Cue processing should no longer be active"

);

  const cueText = "Caption after processing exception";

  const cue = new VTTCue(0, 1, cueText);

  cue.region = new VTTRegion();

  const overlay = document.getElementById("overlay");

  WebVTT.processCues(window, [cue], overlay, null);

  is(overlay.textContent, cueText, "A later cue should still render");

});

</script>

</body>

</html>