Add audio track loading tests (video-dev#1969)

* Put imports at the top of module body

* Add tests for AUDIO_TRACK_LOADING depending on track.url

tests/unit/controller/audio-track-controller.js

@@ -2,6 +2,7 @@ import AudioTrackController from '../../../src/controller/audio-track-controller
 import Hls from '../../../src/hls';
 
 const assert = require('assert');
+const sinon = require('sinon');
 
 describe('AudioTrackController', () => {
   const tracks = [{
@@ -187,6 +188,66 @@ describe('AudioTrackController', () => {
       // name is still the same
       assert.strictEqual(tracks[audioTrackController.audioTrack].name, audioTrackName);
     });
+
+    it('should load audio tracks with a url', () => {
+      const needsTrackLoading = sinon.spy(audioTrackController, '_needsTrackLoading');
+      const audioTrackLoadingCallback = sinon.spy();
+      const trackWithUrl = {
+        groupId: '1',
+        id: 0,
+        name: 'A',
+        default: true,
+        url: './trackA.m3u8'
+      };
+
+      hls.on(Hls.Events.AUDIO_TRACK_LOADING, audioTrackLoadingCallback);
+
+      hls.levelController = {
+        levels: [{
+          urlId: 0,
+          audioGroupIds: ['1']
+        }]
+      };
+
+      audioTrackController.tracks = [trackWithUrl];
+
+      audioTrackController.onLevelLoaded({
+        level: 0
+      });
+
+      sinon.assert.calledOnce(needsTrackLoading);
+      sinon.assert.calledWith(needsTrackLoading, trackWithUrl);
+      assert.strictEqual(needsTrackLoading.firstCall.returnValue, true, 'expected _needsTrackLoading to return true');
+
+      sinon.assert.calledOnce(audioTrackLoadingCallback);
+    });
+
+    it('should not attempt to load audio tracks without a url', () => {
+      const needsTrackLoading = sinon.spy(audioTrackController, '_needsTrackLoading');
+      const audioTrackLoadingCallback = sinon.spy();
+      const trackWithOutUrl = tracks[0];
+
+      hls.on(Hls.Events.AUDIO_TRACK_LOADING, audioTrackLoadingCallback);
+
+      hls.levelController = {
+        levels: [{
+          urlId: 0,
+          audioGroupIds: ['1']
+        }]
+      };
+
+      audioTrackController.tracks = tracks;
+
+      audioTrackController.onLevelLoaded({
+        level: 0
+      });
+
+      sinon.assert.calledOnce(needsTrackLoading);
+      sinon.assert.calledWith(needsTrackLoading, trackWithOutUrl);
+      assert.strictEqual(needsTrackLoading.firstCall.returnValue, false, 'expected _needsTrackLoading to return false');
+
+      sinon.assert.notCalled(audioTrackLoadingCallback);
+    });
   });
 
   describe('onError', () => {