fix: Fallback to isTypeSupported when cast namespace is undefined (sh…

…aka-project#5012)

Resolves shaka-project#5010

---------

Co-authored-by: Dan Sparacio <daniel.sparacio@cbsinteractive.com>

lib/polyfill/media_capabilities.js

@@ -9,7 +9,6 @@ goog.provide('shaka.polyfill.MediaCapabilities');
 goog.require('shaka.log');
 goog.require('shaka.media.Capabilities');
 goog.require('shaka.polyfill');
-goog.require('shaka.util.Error');
 goog.require('shaka.util.Platform');
 
 
@@ -247,13 +246,8 @@ shaka.polyfill.MediaCapabilities = class {
    * @private
    */
   static canCastDisplayType_(videoConfig) {
-    if (!(window.cast)) {
-      shaka.log.error('Expected cast namespace to be available!');
-      throw new shaka.util.Error(
-          shaka.util.Error.Severity.CRITICAL,
-          shaka.util.Error.Category.CAST,
-          shaka.util.Error.Code.CAST_API_UNAVAILABLE);
-    } else if (!(cast.__platform__ && cast.__platform__.canDisplayType)) {
+    if (!(window.cast &&
+        cast.__platform__ && cast.__platform__.canDisplayType)) {
       shaka.log.warning('Expected cast APIs to be available! Falling back to ' +
           'shaka.media.Capabilities.isTypeSupported() for type support.');
       return shaka.media.Capabilities.isTypeSupported(videoConfig.contentType);

test/polyfill/media_capabilities_unit.js

@@ -5,7 +5,6 @@
  */
 
 describe('MediaCapabilities', () => {
-  const Util = shaka.test.Util;
   const originalCast = window['cast'];
   const originalVendor = navigator.vendor;
   const originalUserAgent = navigator.userAgent;
@@ -181,30 +180,30 @@ describe('MediaCapabilities', () => {
           .toHaveBeenCalledTimes(1);
     });
 
-    it('throws when the cast namespace is not available', async () => {
-      // Temporarily remove window.cast to trigger error. It's restored after
-      // every test.
-      delete window['cast'];
+    it('falls back to isTypeSupported() when cast namespace is not available',
+        async () => {
+          // Temporarily remove window.cast to trigger error. It's restored
+          // after every test.
+          delete window['cast'];
 
-      const isChromecastSpy =
-          spyOn(shaka['util']['Platform'],
-              'isChromecast').and.returnValue(true);
-      const expected = Util.jasmineError(new shaka.util.Error(
-          shaka.util.Error.Severity.CRITICAL,
-          shaka.util.Error.Category.CAST,
-          shaka.util.Error.Code.CAST_API_UNAVAILABLE));
-      const isTypeSupportedSpy =
-          spyOn(window['MediaSource'], 'isTypeSupported').and.returnValue(true);
+          const isChromecastSpy =
+              spyOn(shaka['util']['Platform'],
+                  'isChromecast').and.returnValue(true);
+          expect(window['MediaSource']['isTypeSupported']).toBeDefined();
 
-      shaka.polyfill.MediaCapabilities.install();
-      await expectAsync(
-          navigator.mediaCapabilities.decodingInfo(mockDecodingConfig))
-          .toBeRejectedWith(expected);
+          shaka.polyfill.MediaCapabilities.install();
+          await navigator.mediaCapabilities.decodingInfo(mockDecodingConfig);
 
-      expect(isTypeSupportedSpy).not.toHaveBeenCalled();
-      // 1 (during install()) + 1 (for video config check).
-      expect(isChromecastSpy).toHaveBeenCalledTimes(2);
-    });
+          expect(mockCanDisplayType).not.toHaveBeenCalled();
+          // 1 (during install()) + 1 (for video config check).
+          expect(isChromecastSpy).toHaveBeenCalledTimes(2);
+          // 1 (fallback in canCastDisplayType()) +
+          // 1 (mockDecodingConfig.audio).
+          expect(supportMap.has(mockDecodingConfig.video.contentType))
+              .toBe(true);
+          expect(supportMap.has(mockDecodingConfig.audio.contentType))
+              .toBe(true);
+        });
 
     it('falls back to isTypeSupported() when canDisplayType() missing',
         async () => {