test: add a test moving average decaying even without new data

package.json

@@ -13,7 +13,7 @@
  "netlify": "node scripts/netlify.js",
  "build-test": "cross-env-shell TEST_BUNDLE_ONLY=1 'npm run build'",
  "build-prod": "cross-env-shell NO_TEST_BUNDLE=1 'npm run build'",
- "build": "npm-run-all -s clean -p build:*",
+ "build": "npm-run-all -s clean -p build:prod build:test",
  "build:js": "rollup -c scripts/rollup.config.js",
  "docs": "npm-run-all docs:*",
  "docs:api": "jsdoc src -g plugins/markdown -r -d docs/api",
@@ -70,6 +70,7 @@
  },
  "devDependencies": {
  "@rollup/plugin-replace": "^2.3.4",
+ "@rollup/plugin-strip": "^2.0.1",
  "@videojs/generator-helpers": "~2.0.1",
  "d3": "^3.4.8",
  "es5-shim": "^4.5.13",

scripts/rollup.config.js

@@ -3,8 +3,10 @@ const worker = require('rollup-plugin-worker-factory');
 const {terser} = require('rollup-plugin-terser');
 const createTestData = require('./create-test-data.js');
 const replace = require('@rollup/plugin-replace');
+const strip = require('@rollup/plugin-strip');
 
 const CI_TEST_TYPE = process.env.CI_TEST_TYPE || '';
+const NO_TEST_BUNDLE = process.env.NO_TEST_BUNDLE || '';
 
 let syncWorker;
 // see https://github.com/videojs/videojs-generate-rollup-config
@@ -57,6 +59,11 @@ const options = {
  }
  defaults.module.unshift('replace');
 
+ if (NO_TEST_BUNDLE) {
+ defaults.module.unshift('strip');
+ defaults.browser.unshift('strip');
+ }
+
  return defaults;
  },
  primedPlugins(defaults) {
@@ -71,6 +78,9 @@ const options = {
  output: {comments: 'some'},
  compress: {passes: 2}
  }),
+ strip: strip({
+ functions: ['TEST_ONLY_*']
+ }),
  createTestData: createTestData()
  });
 

test/playlist-selectors.test.js

@@ -1,6 +1,7 @@
 import { module, test } from 'qunit';
 import document from 'global/document';
 import {
+ TEST_ONLY_SIMPLE_SELECTOR,
  simpleSelector,
  movingAverageBandwidthSelector,
  minRebufferMaxBandwidthSelector,
@@ -64,6 +65,50 @@ test('Exponential moving average has a configurable decay parameter', function(a
  assert.equal(playlist.attributes.BANDWIDTH, 50, 'selected the middle playlist');
 });
 
+test('Calling exponential moing average wont decay average unless new bandwidth data was provided', function(assert) {
+ let playlist;
+ const simSel = simpleSelector;
+ const bandwidthAverages = [];
+
+ const resetSimpleSelector = TEST_ONLY_SIMPLE_SELECTOR((...args) => {
+ // second argument to simpleSelector is the average
+ bandwidthAverages.push(args[1]);
+ return simSel(...args);
+ });
+
+ this.vhs.playlists.master.playlists = [
+ { attributes: { BANDWIDTH: 1 } },
+ { attributes: { BANDWIDTH: 50 } },
+ { attributes: { BANDWIDTH: 100 } }
+ ];
+
+ const fiftyPercentDecay = movingAverageBandwidthSelector(0.50);
+
+ this.vhs.systemBandwidth = 50 * Config.BANDWIDTH_VARIANCE + 1;
+ playlist = fiftyPercentDecay.call(this.vhs);
+ assert.equal(playlist.attributes.BANDWIDTH, 50, 'selected the middle playlist');
+
+ this.vhs.systemBandwidth = 1000 * Config.BANDWIDTH_VARIANCE + 1;
+ playlist = fiftyPercentDecay.call(this.vhs);
+ assert.equal(playlist.attributes.BANDWIDTH, 100, 'selected the top playlist');
+
+ // using the systemBandwidth values above, 50->1000
+ // we decay into 1000 after 50 iterations
+ let i = 50;
+
+ while (i--) {
+ playlist = fiftyPercentDecay.call(this.vhs);
+ }
+
+ assert.equal(
+ bandwidthAverages[bandwidthAverages.length - 1],
+ bandwidthAverages[1],
+ 'bandwidth should only change when we get new bandwidth data'
+ );
+
+ resetSimpleSelector();
+});
+
 test(
  'minRebufferMaxBandwidthSelector picks highest rendition without rebuffering',
  function(assert) {