chromium/third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/media-elements/playing-the-media-resource/playbackRate.html

<!doctype html>
<title>playbackRate</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id=log></div>
<script>
test(function() {
  var v = document.createElement('video');
  assert_equals(v.playbackRate, 1);
}, 'playbackRate initial value');

function testPlaybackRateHelper(t, newPlaybackRate) {
  var v = document.createElement('video');
  var initialRate = v.playbackRate;

  v.addEventListener('ratechange', t.step_func_done(function() {
    assert_equals(v.playbackRate, newPlaybackRate);
  }));

  try {
    v.playbackRate = newPlaybackRate;
  } catch(e) {
    assert_equals(e.name, 'NotSupportedError');
    assert_equals(v.playbackRate, initialRate);
    t.done();
  }
}

async_test(function(t) {
  testPlaybackRateHelper(this, 3);
}, "playbackRate set to small positive value");

async_test(function(t) {
  testPlaybackRateHelper(this, 100);
}, "playbackRate set to large positive value");

async_test(function(t) {
  testPlaybackRateHelper(this, -3);
}, "playbackRate set to small negative value");

async_test(function(t) {
  testPlaybackRateHelper(this, -100);
}, "playbackRate set to large negative value");

async_test(function(t) {
  testPlaybackRateHelper(this, 0);
}, "playbackRate set to 0");

async_test(function(t) {
  testPlaybackRateHelper(this, -1);
}, "playbackRate set to -1");

</script>