Fix: display error when previewing flash and not enabled

src/i18n/en-US.properties

@@ -62,6 +62,8 @@ error_try_again_later=We're sorry the preview didn't load. Please try again late
 error_bad_file=We're sorry the preview didn't load. This file could not be converted.
 # Preview error message shown when the file cannot be downloaded
 error_not_downloadable=Oops! It looks like something is wrong with this file. We apologize for the inconvenience and recommend that you upload a new version of this file or roll back to a previous version. Please contact us for more details.
+# Preview error message shown when flash is not enabled on their browser
+error_flash_not_enabled=We're sorry, the preview didn't load because Flash is not enabled on your browser. If possible, please enable Flash and refresh the page.
 
 # Media Preview
 # Label for autoplay in media player

src/lib/events.js

@@ -40,7 +40,8 @@ export const ERROR_CODE = {
     CONVERSION_TRY_AGAIN_LATER: 'error_try_again_later',
     CONVERSION_UNSUPPORTED_FORMAT: 'error_unsupported_format',
     VIEWER_LOAD_TIMEOUT: 'error_viewer_load_timeout',
-    CONTENT_DOWNLOAD: 'error_content_download'
+    CONTENT_DOWNLOAD: 'error_content_download',
+    FLASH_NOT_ENABLED: 'error_flash_not_enabled'
 };
 
 export const PREVIEW_LOAD_EVENT = '';

src/lib/viewers/swf/SWFLoader.js

@@ -1,6 +1,9 @@
 import AssetLoader from '../AssetLoader';
 import SWFViewer from './SWFViewer';
 import { ORIGINAL_REP_NAME } from '../../constants';
+import { ERROR_CODE } from '../../events';
+import Browser from '../../Browser';
+import PreviewError from '../../PreviewError';
 
 // Order of the viewers matters. Prefer original before others. Go from specific to general.
 const VIEWERS = [
@@ -21,6 +24,17 @@ class SWFLoader extends AssetLoader {
         super();
         this.viewers = VIEWERS;
     }
+
+    /**
+     * @inheritdoc
+     */
+    determineViewer(file, disabledViewers = []) {
+        if (!Browser.hasFlash()) {
+            throw new PreviewError(ERROR_CODE.FLASH_NOT_ENABLED, __('error_flash_not_enabled'));
+        }
+
+        return super.determineViewer(file, disabledViewers);
+    }
 }
 
 export default new SWFLoader();

src/lib/viewers/swf/__tests__/SWFLoader-test.js

@@ -0,0 +1,26 @@
+import SWFLoader from '../SWFLoader';
+import AssetLoader from '../../AssetLoader';
+import Browser from '../../../Browser';
+import PreviewError from '../../../PreviewError';
+
+const sandbox = sinon.sandbox.create();
+
+describe('lib/viewers/SWFLoader', () => {
+    afterEach(() => {
+        sandbox.verifyAndRestore();
+    });
+
+    describe('determineViewer()', () => {
+        it('should throw a preview error if flash is not supported', () => {
+            sandbox.stub(Browser, 'hasFlash').returns(false);
+            expect(() => SWFLoader.determineViewer()).to.throw(PreviewError);
+        });
+
+        it('should call the superclass determineViewer if flash is suported', () => {
+            sandbox.stub(Browser, 'hasFlash').returns(true);
+            const stub = sandbox.stub(AssetLoader.prototype, 'determineViewer');
+            SWFLoader.determineViewer();
+            expect(stub).to.have.been.called; // eslint-disable-line no-unused-expressions
+        });
+    });
+});