videojs-contrib-hls/test/loader-common.js

import QUnit from 'qunit';
import videojs from 'video.js';
import xhrFactory from '../src/xhr';
import Config from '../src/config';
import {
  playlistWithDuration,
  useFakeEnvironment,
  useFakeMediaSource
} from './test-helpers.js';
import { MasterPlaylistController } from '../src/master-playlist-controller';
import SyncController from '../src/sync-controller';
import Decrypter from '../src/decrypter-worker';
import worker from 'webworkify';

/**
 * beforeEach and afterEach hooks that should be run segment loader tests regardless of
 * the type of loader.
 */
export const LoaderCommonHooks = {
  beforeEach(assert) {
    this.env = useFakeEnvironment(assert);
    this.clock = this.env.clock;
    this.requests = this.env.requests;
    this.mse = useFakeMediaSource();
    this.currentTime = 0;
    this.seekable = {
      length: 0
    };
    this.seeking = false;
    this.hasPlayed = true;
    this.paused = false;
    this.playbackRate = 1;
    this.fakeHls = {
      xhr: xhrFactory(),
      tech_: {
        paused: () => this.paused,
        playbackRate: () => this.playbackRate,
        currentTime: () => this.currentTime
      }
    };
    this.tech_ = this.fakeHls.tech_;
    this.goalBufferLength =
      MasterPlaylistController.prototype.goalBufferLength.bind(this);
    this.mediaSource = new videojs.MediaSource();
    this.mediaSource.trigger('sourceopen');
    this.syncController = new SyncController();
    this.decrypter = worker(Decrypter);
  },
  afterEach(assert) {
    this.env.restore();
    this.mse.restore();
    this.decrypter.terminate();
  }
};

/**
 * Returns a settings object containing the custom settings provided merged with defaults
 * for use in constructing a segment loader. This function should be called with the QUnit
 * test environment the loader will be constructed in for proper this reference.
 *
 * @param {Object} settings
 *        custom settings for the loader
 * @return {Object}
 *         Settings object containing custom settings merged with defaults
 */
export const LoaderCommonSettings = function(settings) {
  return videojs.mergeOptions({
    hls: this.fakeHls,
    currentTime: () => this.currentTime,
    seekable: () => this.seekable,
    seeking: () => this.seeking,
    hasPlayed: () => this.hasPlayed,
    duration: () => this.mediaSource.duration,
    goalBufferLength: () => this.goalBufferLength(),
    mediaSource: this.mediaSource,
    syncController: this.syncController,
    decrypter: this.decrypter
  }, settings);
};

/**
 * Sets up a QUnit module to run tests that should be run on all segment loader types.
 * Currently only two types, SegmentLoader and VTTSegmentLoader.
 *
 * @param {function(new:SegmentLoader|VTTLoader, Object)} LoaderConstructor
 *        Constructor for segment loader. Takes one parameter, a settings object
 * @param {Object} loaderSettings
 *        Custom settings to merge with defaults for the provided loader constructor
 * @param {function(SegmentLoader|VTTLoader)} loaderBeforeEach
 *        Function to be run in the beforeEach after loader creation. Takes one parameter,
 *        the loader for custom modifications to the loader object.
 */
export const LoaderCommonFactory = (LoaderConstructor,
                                    loaderSettings,
                                    loaderBeforeEach) => {
  let loader;

  QUnit.module('Loader Common', function(hooks) {
    hooks.beforeEach(function(assert) {
      // Assume this module is nested and the parent module uses CommonHooks.beforeEach

      loader = new LoaderConstructor(LoaderCommonSettings.call(this, loaderSettings), {});

      loaderBeforeEach(loader);

      // shim updateend trigger to be a noop if the loader has no media source
      this.updateend = function() {
        if (loader.mediaSource_) {
          loader.mediaSource_.sourceBuffers[0].trigger('updateend');
        }
      };
    });

    QUnit.test('fails without required initialization options', function(assert) {
      /* eslint-disable no-new */
      assert.throws(function() {
        new LoaderConstructor();
      }, 'requires options');
      assert.throws(function() {
        new LoaderConstructor({});
      }, 'requires a currentTime callback');
      assert.throws(function() {
        new LoaderConstructor({
          currentTime() {}
        });
      }, 'requires a media source');
      /* eslint-enable */
    });

    QUnit.test('calling load is idempotent', function(assert) {
      loader.playlist(playlistWithDuration(20));

      loader.load();
      this.clock.tick(1);

      assert.equal(loader.state, 'WAITING', 'moves to the ready state');
      assert.equal(this.requests.length, 1, 'made one request');

      loader.load();
      assert.equal(loader.state, 'WAITING', 'still in the ready state');
      assert.equal(this.requests.length, 1, 'still one request');

      // some time passes and a response is received
      this.clock.tick(100);
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');
      loader.load();
      assert.equal(this.requests.length, 0, 'load has no effect');

      // verify stats
      assert.equal(loader.mediaBytesTransferred, 10, '10 bytes');
      assert.equal(loader.mediaTransferDuration, 100, '100 ms (clock above)');
      assert.equal(loader.mediaRequests, 1, '1 request');
    });

    QUnit.test('calling load should unpause', function(assert) {
      loader.playlist(playlistWithDuration(20));
      loader.pause();

      loader.load();
      this.clock.tick(1);
      assert.equal(loader.paused(), false, 'loading unpauses');

      loader.pause();
      this.clock.tick(1);
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');

      assert.equal(loader.paused(), true, 'stayed paused');
      loader.load();
      assert.equal(loader.paused(), false, 'unpaused during processing');

      loader.pause();

      this.updateend();

      assert.equal(loader.state, 'READY', 'finished processing');
      assert.ok(loader.paused(), 'stayed paused');

      loader.load();
      assert.equal(loader.paused(), false, 'unpaused');

      // verify stats
      assert.equal(loader.mediaBytesTransferred, 10, '10 bytes');
      assert.equal(loader.mediaTransferDuration, 1, '1 ms (clock above)');
      assert.equal(loader.mediaRequests, 1, '1 request');
    });

    QUnit.test('regularly checks the buffer while unpaused', function(assert) {
      loader.playlist(playlistWithDuration(90));

      loader.load();
      this.clock.tick(1);

      // fill the buffer
      this.clock.tick(1);
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');

      loader.buffered_ = () => videojs.createTimeRanges([[
        0, Config.GOAL_BUFFER_LENGTH
      ]]);

      this.updateend();

      assert.equal(this.requests.length, 0, 'no outstanding requests');

      // play some video to drain the buffer
      this.currentTime = Config.GOAL_BUFFER_LENGTH;
      this.clock.tick(10 * 1000);
      assert.equal(this.requests.length, 1, 'requested another segment');

      // verify stats
      assert.equal(loader.mediaBytesTransferred, 10, '10 bytes');
      assert.equal(loader.mediaTransferDuration, 1, '1 ms (clock above)');
      assert.equal(loader.mediaRequests, 1, '1 request');
    });

    QUnit.test('does not check the buffer while paused', function(assert) {
      loader.playlist(playlistWithDuration(90));

      loader.load();
      this.clock.tick(1);

      loader.pause();
      this.clock.tick(1);
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');

      this.updateend();

      this.clock.tick(10 * 1000);
      assert.equal(this.requests.length, 0, 'did not make a request');

      // verify stats
      assert.equal(loader.mediaBytesTransferred, 10, '10 bytes');
      assert.equal(loader.mediaTransferDuration, 1, '1 ms (clock above)');
      assert.equal(loader.mediaRequests, 1, '1 request');
    });

    QUnit.test('calculates bandwidth after downloading a segment', function(assert) {
      loader.playlist(playlistWithDuration(10));

      loader.load();
      this.clock.tick(1);

      // some time passes and a response is received
      this.clock.tick(100);
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');

      assert.equal(loader.bandwidth, (10 / 100) * 8 * 1000, 'calculated bandwidth');
      assert.equal(loader.roundTrip, 100, 'saves request round trip time');

      // TODO: Bandwidth Stat will be stale??
      // verify stats
      assert.equal(loader.mediaBytesTransferred, 10, '10 bytes');
      assert.equal(loader.mediaTransferDuration, 100, '100 ms (clock above)');
    });

    QUnit.test('segment request timeouts reset bandwidth', function(assert) {
      loader.playlist(playlistWithDuration(10));

      loader.load();
      this.clock.tick(1);

      // a lot of time passes so the request times out
      this.requests[0].timedout = true;
      this.clock.tick(100 * 1000);

      assert.equal(loader.bandwidth, 1, 'reset bandwidth');
      assert.ok(isNaN(loader.roundTrip), 'reset round trip time');
    });

    QUnit.test('progress on segment requests are redispatched', function(assert) {
      let progressEvents = 0;

      loader.on('progress', function() {
        progressEvents++;
      });
      loader.playlist(playlistWithDuration(10));

      loader.load();
      this.clock.tick(1);

      this.requests[0].dispatchEvent({ type: 'progress', target: this.requests[0] });
      assert.equal(progressEvents, 1, 'triggered progress');
    });

    QUnit.test('aborts request at progress events if bandwidth is too low',
    function(assert) {
      const playlist1 = playlistWithDuration(10, { uri: 'playlist1.m3u8' });
      const playlist2 = playlistWithDuration(10, { uri: 'playlist2.m3u8' });
      const playlist3 = playlistWithDuration(10, { uri: 'playlist3.m3u8' });
      const playlist4 = playlistWithDuration(10, { uri: 'playlist4.m3u8' });
      const xhrOptions = {
        timeout: 15000
      };
      let bandwidthupdates = 0;
      let firstProgress = false;

      playlist1.attributes.BANDWIDTH = 18000;
      playlist2.attributes.BANDWIDTH = 10000;
      playlist3.attributes.BANDWIDTH = 8888;
      playlist4.attributes.BANDWIDTH = 7777;

      loader.hls_.playlists = {
        master: {
          playlists: [
            playlist1,
            playlist2,
            playlist3,
            playlist4
          ]
        }
      };

      const oldHandleProgress = loader.handleProgress_.bind(loader);

      loader.handleProgress_ = (event, simpleSegment) => {
        if (!firstProgress) {
          firstProgress = true;
          assert.equal(simpleSegment.stats.firstBytesReceivedAt, Date.now(),
            'firstBytesReceivedAt timestamp added on first progress event with bytes');
        }
        oldHandleProgress(event, simpleSegment);
      };

      let earlyAborts = 0;

      loader.on('earlyabort', () => earlyAborts++);

      loader.on('bandwidthupdate', () => bandwidthupdates++);
      loader.playlist(playlist1, xhrOptions);
      loader.load();

      this.clock.tick(1);

      this.requests[0].dispatchEvent({
        type: 'progress',
        target: this.requests[0],
        loaded: 1
      });

      assert.equal(bandwidthupdates, 0, 'no bandwidth updates yet');
      assert.notOk(this.requests[0].aborted, 'request not prematurely aborted');
      assert.equal(earlyAborts, 0, 'no earlyabort events');

      this.clock.tick(999);

      this.requests[0].dispatchEvent({
        type: 'progress',
        target: this.requests[0],
        loaded: 2000
      });

      assert.equal(bandwidthupdates, 0, 'no bandwidth updates yet');
      assert.notOk(this.requests[0].aborted, 'request not prematurely aborted');
      assert.equal(earlyAborts, 0, 'no earlyabort events');

      this.clock.tick(2);

      this.requests[0].dispatchEvent({
        type: 'progress',
        target: this.requests[0],
        loaded: 2001
      });

      assert.equal(bandwidthupdates, 0, 'bandwidth not updated');
      assert.ok(this.requests[0].aborted, 'request aborted');
      assert.equal(earlyAborts, 1, 'earlyabort event triggered');
    });

    QUnit.test(
      'appending a segment when loader is in walk-forward mode triggers bandwidthupdate',
    function(assert) {
      let progresses = 0;

      loader.on('bandwidthupdate', function() {
        progresses++;
      });
      loader.playlist(playlistWithDuration(20));

      loader.load();
      this.clock.tick(1);

      // some time passes and a response is received
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');

      this.updateend();

      assert.equal(progresses, 0, 'no bandwidthupdate fired');

      this.clock.tick(2);
      // if mediaIndex is set, then the SegmentLoader is in walk-forward mode
      loader.mediaIndex = 1;

      // some time passes and a response is received
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');

      this.updateend();

      assert.equal(progresses, 1, 'fired bandwidthupdate');

      // verify stats
      assert.equal(loader.mediaBytesTransferred, 20, '20 bytes');
      assert.equal(loader.mediaRequests, 2, '2 request');
    });

    QUnit.test('only requests one segment at a time', function(assert) {
      loader.playlist(playlistWithDuration(10));

      loader.load();
      this.clock.tick(1);

      // a bunch of time passes without recieving a response
      this.clock.tick(20 * 1000);
      assert.equal(this.requests.length, 1, 'only one request was made');
    });

    QUnit.test('downloads init segments if specified', function(assert) {
      let playlist = playlistWithDuration(20);
      let map = {
        resolvedUri: 'mainInitSegment',
        byterange: {
          length: 20,
          offset: 0
        }
      };

      let buffered = videojs.createTimeRanges();

      loader.buffered_ = () => buffered;

      playlist.segments[0].map = map;
      playlist.segments[1].map = map;
      loader.playlist(playlist);

      loader.load();
      this.clock.tick(1);

      assert.equal(this.requests.length, 2, 'made requests');

      // init segment response
      this.clock.tick(1);
      assert.equal(this.requests[0].url, 'mainInitSegment', 'requested the init segment');
      this.requests[0].response = new Uint8Array(20).buffer;
      this.requests.shift().respond(200, null, '');
      // 0.ts response
      this.clock.tick(1);
      assert.equal(this.requests[0].url, '0.ts',
                  'requested the segment');
      this.requests[0].response = new Uint8Array(20).buffer;
      this.requests.shift().respond(200, null, '');

      // append the init segment
      buffered = videojs.createTimeRanges([]);
      this.updateend();

      // append the segment
      buffered = videojs.createTimeRanges([[0, 10]]);
      this.updateend();
      this.clock.tick(1);

      assert.equal(this.requests.length, 1, 'made a request');
      assert.equal(this.requests[0].url, '1.ts',
                  'did not re-request the init segment');
    });

    QUnit.test('detects init segment changes and downloads it', function(assert) {
      let playlist = playlistWithDuration(20);
      let buffered = videojs.createTimeRanges();

      playlist.segments[0].map = {
        resolvedUri: 'init0',
        byterange: {
          length: 20,
          offset: 0
        }
      };
      playlist.segments[1].map = {
        resolvedUri: 'init0',
        byterange: {
          length: 20,
          offset: 20
        }
      };

      loader.buffered_ = () => buffered;
      loader.playlist(playlist);

      loader.load();
      this.clock.tick(1);

      assert.equal(this.requests.length, 2, 'made requests');

      // init segment response
      this.clock.tick(1);
      assert.equal(this.requests[0].url, 'init0', 'requested the init segment');
      assert.equal(this.requests[0].headers.Range, 'bytes=0-19',
                  'requested the init segment byte range');
      this.requests[0].response = new Uint8Array(20).buffer;
      this.requests.shift().respond(200, null, '');
      // 0.ts response
      this.clock.tick(1);
      assert.equal(this.requests[0].url, '0.ts',
                  'requested the segment');
      this.requests[0].response = new Uint8Array(20).buffer;
      this.requests.shift().respond(200, null, '');

      // append the init segment
      buffered = videojs.createTimeRanges([]);
      this.updateend();
      // append the segment
      buffered = videojs.createTimeRanges([[0, 10]]);
      this.updateend();
      this.clock.tick(1);

      assert.equal(this.requests.length, 2, 'made requests');
      assert.equal(this.requests[0].url, 'init0', 'requested the init segment');
      assert.equal(this.requests[0].headers.Range, 'bytes=20-39',
                  'requested the init segment byte range');
      assert.equal(this.requests[1].url, '1.ts',
                  'did not re-request the init segment');
    });

    QUnit.test('request error increments mediaRequestsErrored stat', function(assert) {
      loader.playlist(playlistWithDuration(20));

      loader.load();
      this.clock.tick(1);

      this.requests.shift().respond(404, null, '');

      // verify stats
      assert.equal(loader.mediaRequests, 1, '1 request');
      assert.equal(loader.mediaRequestsErrored, 1, '1 errored request');
    });

    QUnit.test('request timeout increments mediaRequestsTimedout stat', function(assert) {
      loader.playlist(playlistWithDuration(20));

      loader.load();
      this.clock.tick(1);
      this.requests[0].timedout = true;
      this.clock.tick(100 * 1000);

      // verify stats
      assert.equal(loader.mediaRequests, 1, '1 request');
      assert.equal(loader.mediaRequestsTimedout, 1, '1 timed-out request');
    });

    QUnit.test('request abort increments mediaRequestsAborted stat', function(assert) {
      loader.playlist(playlistWithDuration(20));

      loader.load();
      this.clock.tick(1);

      loader.abort();
      this.clock.tick(1);

      // verify stats
      assert.equal(loader.mediaRequests, 1, '1 request');
      assert.equal(loader.mediaRequestsAborted, 1, '1 aborted request');
    });

    QUnit.test('SegmentLoader.mediaIndex is adjusted when live playlist is updated',
    function(assert) {
      loader.playlist(playlistWithDuration(50, {
        mediaSequence: 0,
        endList: false
      }));

      loader.load();
      // Start at mediaIndex 2 which means that the next segment we request
      // should mediaIndex 3
      loader.mediaIndex = 2;
      this.clock.tick(1);

      assert.equal(loader.mediaIndex, 2, 'SegmentLoader.mediaIndex starts at 2');
      assert.equal(this.requests[0].url,
                   '3.ts',
                   'requesting the segment at mediaIndex 3');

      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');
      this.clock.tick(1);
      this.updateend();

      assert.equal(loader.mediaIndex, 3, 'mediaIndex ends at 3');

      this.clock.tick(1);

      assert.equal(loader.mediaIndex, 3, 'SegmentLoader.mediaIndex starts at 3');
      assert.equal(this.requests[0].url,
                   '4.ts',
                   'requesting the segment at mediaIndex 4');

      // Update the playlist shifting the mediaSequence by 2 which will result
      // in a decrement of the mediaIndex by 2 to 1
      loader.playlist(playlistWithDuration(50, {
        mediaSequence: 2,
        endList: false
      }));

      assert.equal(loader.mediaIndex, 1, 'SegmentLoader.mediaIndex is updated to 1');

      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');
      this.clock.tick(1);
      this.updateend();

      assert.equal(loader.mediaIndex, 2, 'SegmentLoader.mediaIndex ends at 2');
    });

    QUnit.test('segmentInfo.mediaIndex is adjusted when live playlist is updated',
    function(assert) {
      const handleUpdateEnd_ = loader.handleUpdateEnd_.bind(loader);
      let expectedLoaderIndex = 3;

      loader.handleUpdateEnd_ = function() {
        handleUpdateEnd_();

        assert.equal(loader.mediaIndex,
                     expectedLoaderIndex,
                     'SegmentLoader.mediaIndex ends at' + expectedLoaderIndex);
        loader.mediaIndex = null;
        loader.fetchAtBuffer_ = false;
        // remove empty flag that may be added by vtt loader
        loader.playlist_.segments.forEach(segment => segment.empty = false);
      };

      // Setting currentTime to 31 so that we start requesting at segment #3
      this.currentTime = 31;
      loader.playlist(playlistWithDuration(50, {
        mediaSequence: 0,
        endList: false
      }));

      loader.load();
      // Start at mediaIndex null which means that the next segment we request
      // should be based on currentTime (mediaIndex 3)
      loader.mediaIndex = null;
      loader.syncPoint_ = {
        segmentIndex: 0,
        time: 0
      };
      this.clock.tick(1);

      let segmentInfo = loader.pendingSegment_;

      assert.equal(segmentInfo.mediaIndex, 3, 'segmentInfo.mediaIndex starts at 3');
      assert.equal(this.requests[0].url,
                   '3.ts',
                   'requesting the segment at mediaIndex 3');

      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');
      this.clock.tick(1);
      this.updateend();

      this.clock.tick(1);
      segmentInfo = loader.pendingSegment_;

      assert.equal(segmentInfo.mediaIndex, 3, 'segmentInfo.mediaIndex starts at 3');
      assert.equal(this.requests[0].url,
                   '3.ts',
                   'requesting the segment at mediaIndex 3');

      // Update the playlist shifting the mediaSequence by 2 which will result
      // in a decrement of the mediaIndex by 2 to 1
      loader.playlist(playlistWithDuration(50, {
        mediaSequence: 2,
        endList: false
      }));

      assert.equal(segmentInfo.mediaIndex, 1, 'segmentInfo.mediaIndex is updated to 1');

      expectedLoaderIndex = 1;
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');
      this.clock.tick(1);
      this.updateend();
    });

    QUnit.test('segment 404s should trigger an error', function(assert) {
      let errors = [];

      loader.playlist(playlistWithDuration(10));

      loader.load();
      this.clock.tick(1);

      loader.on('error', function(error) {
        errors.push(error);
      });
      this.requests.shift().respond(404, null, '');

      assert.equal(errors.length, 1, 'triggered an error');
      assert.equal(loader.error().code, 2, 'triggered MEDIA_ERR_NETWORK');
      assert.ok(loader.error().xhr, 'included the request object');
      assert.ok(loader.paused(), 'paused the loader');
      assert.equal(loader.state, 'READY', 'returned to the ready state');
    });

    QUnit.test('empty segments should trigger an error', function(assert) {
      let errors = [];

      loader.playlist(playlistWithDuration(10));

      loader.load();
      this.clock.tick(1);

      loader.on('error', function(error) {
        errors.push(error);
      });
      this.requests[0].response = new Uint8Array(0).buffer;
      this.requests.shift().respond(200, null, '');

      assert.equal(errors.length, 1, 'triggered an error');
      assert.equal(loader.error().code, 2, 'triggered MEDIA_ERR_NETWORK');
      assert.ok(loader.error().xhr, 'included the request object');
      assert.ok(loader.paused(), 'paused the loader');
      assert.equal(loader.state, 'READY', 'returned to the ready state');
    });

    QUnit.test('segment 5xx status codes trigger an error', function(assert) {
      let errors = [];

      loader.playlist(playlistWithDuration(10));

      loader.load();
      this.clock.tick(1);

      loader.on('error', function(error) {
        errors.push(error);
      });
      this.requests.shift().respond(500, null, '');

      assert.equal(errors.length, 1, 'triggered an error');
      assert.equal(loader.error().code, 2, 'triggered MEDIA_ERR_NETWORK');
      assert.ok(loader.error().xhr, 'included the request object');
      assert.ok(loader.paused(), 'paused the loader');
      assert.equal(loader.state, 'READY', 'returned to the ready state');
    });

    QUnit.test('remains ready if there are no segments', function(assert) {
      loader.playlist(playlistWithDuration(0));

      loader.load();
      this.clock.tick(1);

      assert.equal(loader.state, 'READY', 'in the ready state');
    });

    QUnit.test('dispose cleans up outstanding work', function(assert) {
      loader.playlist(playlistWithDuration(20));

      loader.load();
      this.clock.tick(1);

      loader.dispose();
      assert.ok(this.requests[0].aborted, 'aborted segment request');
      assert.equal(this.requests.length, 1, 'did not open another request');

      // Check that media source was properly cleaned up if it exists on the loader
      if (loader.mediaSource_) {
        loader.mediaSource_.sourceBuffers.forEach((sourceBuffer, i) => {
          let lastOperation = sourceBuffer.updates_.slice(-1)[0];

          assert.ok(lastOperation.abort, 'aborted source buffer ' + i);
        });
      }
    });

    // ----------
    // Decryption
    // ----------

    QUnit.test('calling load with an encrypted segment requests key and segment',
    function(assert) {
      assert.equal(loader.state, 'INIT', 'starts in the init state');
      loader.playlist(playlistWithDuration(10, {isEncrypted: true}));
      assert.equal(loader.state, 'INIT', 'starts in the init state');
      assert.ok(loader.paused(), 'starts paused');

      loader.load();
      this.clock.tick(1);

      assert.equal(loader.state, 'WAITING', 'moves to the ready state');
      assert.ok(!loader.paused(), 'loading is not paused');
      assert.equal(this.requests.length, 2, 'requested a segment and key');
      assert.equal(this.requests[0].url,
                   '0-key.php',
                   'requested the first segment\'s key');
      assert.equal(this.requests[1].url, '0.ts', 'requested the first segment');
    });

    QUnit.test('dispose cleans up key requests for encrypted segments', function(assert) {
      loader.playlist(playlistWithDuration(20, {isEncrypted: true}));

      loader.load();
      this.clock.tick(1);

      loader.dispose();
      assert.equal(this.requests.length, 2, 'requested a segment and key');
      assert.equal(this.requests[0].url,
                   '0-key.php',
                   'requested the first segment\'s key');
      assert.ok(this.requests[0].aborted, 'aborted the first segment\s key request');
      assert.equal(this.requests.length, 2, 'did not open another request');
    });

    QUnit.test('key 404s should trigger an error', function(assert) {
      let errors = [];

      loader.playlist(playlistWithDuration(10, {isEncrypted: true}));

      loader.load();
      this.clock.tick(1);

      loader.on('error', function(error) {
        errors.push(error);
      });
      this.requests.shift().respond(404, null, '');
      this.clock.tick(1);

      assert.equal(errors.length, 1, 'triggered an error');
      assert.equal(loader.error().code, 2, 'triggered MEDIA_ERR_NETWORK');
      assert.equal(loader.error().message, 'HLS request errored at URL: 0-key.php',
            'receieved a key error message');
      assert.ok(loader.error().xhr, 'included the request object');
      assert.ok(loader.paused(), 'paused the loader');
      assert.equal(loader.state, 'READY', 'returned to the ready state');
    });

    QUnit.test('key 5xx status codes trigger an error', function(assert) {
      let errors = [];

      loader.playlist(playlistWithDuration(10, {isEncrypted: true}));

      loader.load();
      this.clock.tick(1);

      loader.on('error', function(error) {
        errors.push(error);
      });
      this.requests.shift().respond(500, null, '');

      assert.equal(errors.length, 1, 'triggered an error');
      assert.equal(loader.error().code, 2, 'triggered MEDIA_ERR_NETWORK');
      assert.equal(loader.error().message, 'HLS request errored at URL: 0-key.php',
            'receieved a key error message');
      assert.ok(loader.error().xhr, 'included the request object');
      assert.ok(loader.paused(), 'paused the loader');
      assert.equal(loader.state, 'READY', 'returned to the ready state');
    });

    QUnit.test('key request timeouts reset bandwidth', function(assert) {
      loader.playlist(playlistWithDuration(10, {isEncrypted: true}));

      loader.load();
      this.clock.tick(1);

      assert.equal(this.requests[0].url,
                   '0-key.php',
                   'requested the first segment\'s key');
      assert.equal(this.requests[1].url, '0.ts', 'requested the first segment');
      // a lot of time passes so the request times out
      this.requests[0].timedout = true;
      this.clock.tick(100 * 1000);

      assert.equal(loader.bandwidth, 1, 'reset bandwidth');
      assert.ok(isNaN(loader.roundTrip), 'reset round trip time');
    });

    QUnit.test('checks the goal buffer configuration every loading opportunity',
    function(assert) {
      let playlist = playlistWithDuration(20);
      let defaultGoal = Config.GOAL_BUFFER_LENGTH;
      let segmentInfo;

      Config.GOAL_BUFFER_LENGTH = 1;
      loader.playlist(playlist);

      loader.load();

      segmentInfo = loader.checkBuffer_(videojs.createTimeRanges([[0, 1]]),
                                        playlist,
                                        null,
                                        loader.hasPlayed_(),
                                        0,
                                        null);
      assert.ok(!segmentInfo, 'no request generated');
      Config.GOAL_BUFFER_LENGTH = defaultGoal;
    });

    QUnit.test(
      'does not skip over segment if live playlist update occurs while processing',
    function(assert) {
      let playlist = playlistWithDuration(40);
      let buffered = videojs.createTimeRanges();

      loader.buffered_ = () => buffered;

      playlist.endList = false;

      loader.playlist(playlist);

      loader.load();
      this.clock.tick(1);

      assert.equal(loader.pendingSegment_.uri, '0.ts', 'retrieving first segment');
      assert.equal(loader.pendingSegment_.segment.uri,
                   '0.ts',
                   'correct segment reference');
      assert.equal(loader.state, 'WAITING', 'waiting for response');

      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');
      // playlist updated during append
      let playlistUpdated = playlistWithDuration(40);

      playlistUpdated.segments.shift();
      playlistUpdated.mediaSequence++;
      loader.playlist(playlistUpdated);
      // finish append
      buffered = videojs.createTimeRanges([[0, 10]]);
      this.updateend();
      this.clock.tick(1);

      assert.equal(loader.pendingSegment_.uri, '1.ts', 'retrieving second segment');
      assert.equal(loader.pendingSegment_.segment.uri,
                   '1.ts',
                   'correct segment reference');
      assert.equal(loader.state, 'WAITING', 'waiting for response');
    });

    QUnit.test('processing segment reachable even after playlist update removes it',
    function(assert) {
      const handleUpdateEnd_ = loader.handleUpdateEnd_.bind(loader);
      let expectedURI = '0.ts';
      let playlist = playlistWithDuration(40);
      let buffered = videojs.createTimeRanges();

      loader.handleUpdateEnd_ = () => {
        // we need to check for the right state, as normally handleResponse would throw an
        // error under failing cases, but sinon swallows it as part of fake XML HTTP
        // request's response
        assert.equal(loader.state, 'APPENDING', 'moved to appending state');
        assert.equal(loader.pendingSegment_.uri, expectedURI, 'correct pending segment');
        assert.equal(loader.pendingSegment_.segment.uri,
                     expectedURI,
                     'correct segment reference');

        handleUpdateEnd_();
      };

      loader.buffered_ = () => buffered;

      playlist.endList = false;

      loader.playlist(playlist);

      loader.load();
      this.clock.tick(1);

      assert.equal(loader.state, 'WAITING', 'in waiting state');
      assert.equal(loader.pendingSegment_.uri, '0.ts', 'first segment pending');
      assert.equal(loader.pendingSegment_.segment.uri,
                   '0.ts',
                   'correct segment reference');

      // wrap up the first request to set mediaIndex and start normal live streaming
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');
      buffered = videojs.createTimeRanges([[0, 10]]);
      this.updateend();
      this.clock.tick(1);

      assert.equal(loader.state, 'WAITING', 'in waiting state');
      assert.equal(loader.pendingSegment_.uri, '1.ts', 'second segment pending');
      assert.equal(loader.pendingSegment_.segment.uri,
                   '1.ts',
                   'correct segment reference');

      // playlist updated during waiting
      let playlistUpdated = playlistWithDuration(40);

      playlistUpdated.segments.shift();
      playlistUpdated.segments.shift();
      playlistUpdated.mediaSequence += 2;
      loader.playlist(playlistUpdated);

      assert.equal(loader.pendingSegment_.uri, '1.ts', 'second segment still pending');
      assert.equal(loader.pendingSegment_.segment.uri,
                   '1.ts',
                   'correct segment reference');

      expectedURI = '1.ts';
      this.requests[0].response = new Uint8Array(10).buffer;
      this.requests.shift().respond(200, null, '');
      this.updateend();
    });

    QUnit.test('new playlist always triggers syncinfoupdate', function(assert) {
      let playlist = playlistWithDuration(100, { endList: false });
      let syncInfoUpdates = 0;

      loader.on('syncinfoupdate', () => syncInfoUpdates++);

      loader.playlist(playlist);

      loader.load();

      assert.equal(syncInfoUpdates, 1, 'first playlist triggers an update');
      loader.playlist(playlist);
      assert.equal(syncInfoUpdates, 2, 'same playlist triggers an update');
      playlist = playlistWithDuration(100, { endList: false });
      loader.playlist(playlist);
      assert.equal(syncInfoUpdates, 3, 'new playlist with same info triggers an update');
      playlist.segments[0].start = 10;
      playlist = playlistWithDuration(100, { endList: false, mediaSequence: 1 });
      loader.playlist(playlist);
      assert.equal(syncInfoUpdates,
                   5,
                   'new playlist after expiring segment triggers two updates');
    });

    QUnit.module('Loading Calculation');

    QUnit.test('requests the first segment with an empty buffer', function(assert) {

      let segmentInfo = loader.checkBuffer_(videojs.createTimeRanges(),
                                            playlistWithDuration(20),
                                            null,
                                            loader.hasPlayed_(),
                                            0,
                                            null);

      assert.ok(segmentInfo, 'generated a request');
      assert.equal(segmentInfo.uri, '0.ts', 'requested the first segment');
    });

    QUnit.test('no request if video not played and 1 segment is buffered',
    function(assert) {
      this.hasPlayed = false;

      let segmentInfo = loader.checkBuffer_(videojs.createTimeRanges([[0, 1]]),
                                            playlistWithDuration(20),
                                            0,
                                            loader.hasPlayed_(),
                                            0,
                                            null);

      assert.ok(!segmentInfo, 'no request generated');
    });

    QUnit.test('does not download the next segment if the buffer is full',
    function(assert) {
      let buffered;
      let segmentInfo;

      buffered = videojs.createTimeRanges([
        [0, 30 + Config.GOAL_BUFFER_LENGTH]
      ]);
      segmentInfo = loader.checkBuffer_(buffered,
                                        playlistWithDuration(30),
                                        null,
                                        true,
                                        15,
                                        { segmentIndex: 0, time: 0 });

      assert.ok(!segmentInfo, 'no segment request generated');
    });

    QUnit.test('downloads the next segment if the buffer is getting low',
    function(assert) {
      let buffered;
      let segmentInfo;
      let playlist = playlistWithDuration(30);

      loader.playlist(playlist);

      buffered = videojs.createTimeRanges([[0, 19.999]]);
      segmentInfo = loader.checkBuffer_(buffered,
                                        playlist,
                                        1,
                                        true,
                                        15,
                                        { segmentIndex: 0, time: 0 });

      assert.ok(segmentInfo, 'made a request');
      assert.equal(segmentInfo.uri, '2.ts', 'requested the third segment');
    });

    QUnit.test('stops downloading segments at the end of the playlist', function(assert) {
      let buffered;
      let segmentInfo;

      buffered = videojs.createTimeRanges([[0, 60]]);
      segmentInfo = loader.checkBuffer_(buffered,
                                        playlistWithDuration(60),
                                        null,
                                        true,
                                        0,
                                        null);

      assert.ok(!segmentInfo, 'no request was made');
    });

    QUnit.test('stops downloading segments if buffered past reported end of the playlist',
    function(assert) {
      let buffered;
      let segmentInfo;
      let playlist;

      buffered = videojs.createTimeRanges([[0, 59.9]]);
      playlist = playlistWithDuration(60);
      playlist.segments[playlist.segments.length - 1].end = 59.9;
      segmentInfo = loader.checkBuffer_(buffered,
                                        playlist,
                                        playlist.segments.length - 1,
                                        true,
                                        50,
                                        { segmentIndex: 0, time: 0 });

      assert.ok(!segmentInfo, 'no request was made');
    });

    QUnit.test('doesn\'t allow more than one monitor buffer timer to be set',
    function(assert) {
      let timeoutCount = this.clock.methods.length;

      loader.monitorBuffer_();

      assert.equal(this.clock.methods.length,
                   timeoutCount,
                   'timeout count remains the same');

      loader.monitorBuffer_();

      assert.equal(this.clock.methods.length,
                   timeoutCount,
                   'timeout count remains the same');

      loader.monitorBuffer_();
      loader.monitorBuffer_();

      assert.equal(this.clock.methods.length,
                   timeoutCount,
                   'timeout count remains the same');
    });
  });
};