Metadata cues may have length zero (#113)

* Metadata cues may have length zero
It's not safe to assume that there is at least one element in metadata cues when addTextTrackData() is invoked. Double check the array is there and non-empty before tweaking start and end times. Add tests for that module.

* Fix another bad array length check
Empty arrays are truthy.

src/add-text-track-data.js

@@ -93,11 +93,12 @@ const addTextTrackData = function(sourceHandler, captionArray, metadataArray) {
       }, this);
     }, sourceHandler);
 
-    /** Updating the metadeta cues so that
-     * the endTime of each cue is the startTime of the next cue
-     * the endTime of last cue is the duration of the video
-     */
-    if (sourceHandler.metadataTrack_ && sourceHandler.metadataTrack_.cues) {
+    // Updating the metadeta cues so that
+    // the endTime of each cue is the startTime of the next cue
+    // the endTime of last cue is the duration of the video
+    if (sourceHandler.metadataTrack_ &&
+        sourceHandler.metadataTrack_.cues &&
+        sourceHandler.metadataTrack_.cues.length) {
       let cues = sourceHandler.metadataTrack_.cues;
       let cuesArray = [];
 

src/html-media-source.js

@@ -198,7 +198,7 @@ export default class HtmlMediaSource extends videojs.EventTarget {
         let sourcebuffer = this.sourceBuffers[i];
         let cues = sourcebuffer.metadataTrack_ && sourcebuffer.metadataTrack_.cues;
 
-        if (cues) {
+        if (cues && cues.length) {
           cues[cues.length - 1].endTime = duration;
         }
       }

test/add-text-track-data.test.js

@@ -0,0 +1,51 @@
+import Qunit from 'qunit';
+import { addTextTrackData } from '../src/add-text-track-data';
+
+const { equal, module, test } = Qunit;
+
+class MockTextTrack {
+  constructor() {
+    this.cues = [];
+  }
+  addCue(cue) {
+    this.cues.push(cue);
+  }
+}
+
+module('Text Track Data', {
+  beforeEach() {
+    this.sourceHandler = {
+      inbandTextTrack_: new MockTextTrack(),
+      metadataTrack_: new MockTextTrack(),
+      mediaSource_: {
+        duration: NaN
+      },
+      timestampOffset: 0
+    };
+  }
+});
+
+test('does nothing if no cues are specified', function() {
+  addTextTrackData(this.sourceHandler, [], []);
+  equal(this.sourceHandler.inbandTextTrack_.cues.length, 0, 'added no 608 cues');
+  equal(this.sourceHandler.metadataTrack_.cues.length, 0, 'added no metadata cues');
+});
+
+test('creates cues for 608 captions', function() {
+  addTextTrackData(this.sourceHandler, [{
+    startTime: 0,
+    endTime: 1,
+    text: 'caption text'
+  }], []);
+  equal(this.sourceHandler.inbandTextTrack_.cues.length, 1, 'added one 608 cues');
+  equal(this.sourceHandler.metadataTrack_.cues.length, 0, 'added no metadata cues');
+});
+
+test('creates cues for timed metadata', function() {
+  addTextTrackData(this.sourceHandler, [], [{
+    cueTime: 1,
+    frames: [{}]
+  }]);
+  equal(this.sourceHandler.inbandTextTrack_.cues.length, 0, 'added no 608 cues');
+  equal(this.sourceHandler.metadataTrack_.cues.length, 1, 'added one metadata cues');
+});