gecko-dev/dom/media/tests/mochitest/mediaStreamPlayback.js

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

const ENDED_TIMEOUT_LENGTH = 30000;

/* The time we wait depends primarily on the canplaythrough event firing
 * Note: this needs to be at least 30s because the
 *       B2G emulator in VMs is really slow. */
const VERIFYPLAYING_TIMEOUT_LENGTH = 60000;

/**
 * This class manages playback of a HTMLMediaElement with a MediaStream.
 * When constructed by a caller, an object instance is created with
 * a media element and a media stream object.
 *
 * @param {HTMLMediaElement} mediaElement the media element for playback
 * @param {MediaStream} mediaStream the media stream used in
 *                                  the mediaElement for playback
 */
function MediaStreamPlayback(mediaElement, mediaStream) {
  this.mediaElement = mediaElement;
  this.mediaStream = mediaStream;
}

MediaStreamPlayback.prototype = {
  /**
   * Starts media element with a media stream, runs it until a canplaythrough
   * and timeupdate event fires, and calls stop() on all its tracks.
   *
   * @param {Boolean} isResume specifies if this media element is being resumed
   *                           from a previous run
   */
  playMedia(isResume) {
    this.startMedia(isResume);
    return this.verifyPlaying()
      .then(() => this.stopTracksForStreamInMediaPlayback())
      .then(() => this.detachFromMediaElement());
  },

  /**
   * Stops the local media stream's tracks while it's currently in playback in
   * a media element.
   *
   * Precondition: The media stream and element should both be actively
   *               being played. All the stream's tracks must be local.
   */
  stopTracksForStreamInMediaPlayback() {
    var elem = this.mediaElement;
    return Promise.all([
      haveEvent(
        elem,
        "ended",
        wait(ENDED_TIMEOUT_LENGTH, new Error("Timeout"))
      ),
      ...this.mediaStream
        .getTracks()
        .map(t => (t.stop(), haveNoEvent(t, "ended"))),
    ]);
  },

  /**
   * Starts media with a media stream, runs it until a canplaythrough and
   * timeupdate event fires, and detaches from the element without stopping media.
   *
   * @param {Boolean} isResume specifies if this media element is being resumed
   *                           from a previous run
   */
  playMediaWithoutStoppingTracks(isResume) {
    this.startMedia(isResume);
    return this.verifyPlaying().then(() => this.detachFromMediaElement());
  },

  /**
   * Starts the media with the associated stream.
   *
   * @param {Boolean} isResume specifies if the media element playback
   *                           is being resumed from a previous run
   */
  startMedia(isResume) {
    // If we're playing media element for the first time, check that time is zero.
    if (!isResume) {
      is(
        this.mediaElement.currentTime,
        0,
        "Before starting the media element, currentTime = 0"
      );
    }
    this.canPlayThroughFired = listenUntil(
      this.mediaElement,
      "canplaythrough",
      () => true
    );

    // Hooks up the media stream to the media element and starts playing it
    this.mediaElement.srcObject = this.mediaStream;
    this.mediaElement.play();
  },

  /**
   * Verifies that media is playing.
   */
  verifyPlaying() {
    var lastElementTime = this.mediaElement.currentTime;

    var mediaTimeProgressed = listenUntil(
      this.mediaElement,
      "timeupdate",
      () => this.mediaElement.currentTime > lastElementTime
    );

    return timeout(
      Promise.all([this.canPlayThroughFired, mediaTimeProgressed]),
      VERIFYPLAYING_TIMEOUT_LENGTH,
      "verifyPlaying timed out"
    ).then(() => {
      is(this.mediaElement.paused, false, "Media element should be playing");
      is(
        this.mediaElement.duration,
        Number.POSITIVE_INFINITY,
        "Duration should be infinity"
      );

      // When the media element is playing with a real-time stream, we
      // constantly switch between having data to play vs. queuing up data,
      // so we can only check that the ready state is one of those two values
      ok(
        this.mediaElement.readyState === HTMLMediaElement.HAVE_ENOUGH_DATA ||
          this.mediaElement.readyState === HTMLMediaElement.HAVE_CURRENT_DATA,
        "Ready state shall be HAVE_ENOUGH_DATA or HAVE_CURRENT_DATA"
      );

      is(this.mediaElement.seekable.length, 0, "Seekable length shall be zero");
      is(this.mediaElement.buffered.length, 0, "Buffered length shall be zero");

      is(
        this.mediaElement.seeking,
        false,
        "MediaElement is not seekable with MediaStream"
      );
      ok(
        isNaN(this.mediaElement.startOffsetTime),
        "Start offset time shall not be a number"
      );
      is(
        this.mediaElement.defaultPlaybackRate,
        1,
        "DefaultPlaybackRate should be 1"
      );
      is(this.mediaElement.playbackRate, 1, "PlaybackRate should be 1");
      is(this.mediaElement.preload, "none", 'Preload should be "none"');
      is(this.mediaElement.src, "", "No src should be defined");
      is(
        this.mediaElement.currentSrc,
        "",
        "Current src should still be an empty string"
      );
    });
  },

  /**
   * Detaches from the element without stopping the media.
   *
   * Precondition: The media stream and element should both be actively
   *               being played.
   */
  detachFromMediaElement() {
    this.mediaElement.pause();
    this.mediaElement.srcObject = null;
  },
};

// haxx to prevent SimpleTest from failing at window.onload
function addLoadEvent() {}

var scriptsReady = Promise.all(
  ["/tests/SimpleTest/SimpleTest.js", "head.js"].map(script => {
    var el = document.createElement("script");
    el.src = script;
    document.head.appendChild(el);
    return new Promise(r => (el.onload = r));
  })
);

function createHTML(options) {
  return scriptsReady.then(() => realCreateHTML(options));
}

// noGum - Helper to detect whether active guM tracks still exist.
//
// It relies on the fact that, by spec, device labels from enumerateDevices are
// only visible during active gum calls. They're also visible when persistent
// permissions are granted, so turn off media.navigator.permission.disabled
// (which is normally on otherwise in our tests). Lastly, we must turn on
// media.navigator.permission.fake otherwise fake devices don't count as active.

var noGum = () =>
  pushPrefs(
    ["media.navigator.permission.disabled", false],
    ["media.navigator.permission.fake", true],
    ["media.devices.insecure.enabled", true]
  )
    .then(() => navigator.mediaDevices.enumerateDevices())
    .then(
      ([device]) =>
        device &&
        is(device.label, "", "Test must leave no active gUM streams behind.")
    );

var runTest = testFunction =>
  scriptsReady
    .then(() => runTestWhenReady(testFunction))
    .then(() => noGum())
    .then(() => finish());