tests: fix test missing assertion

Author: dougwilson

test/res.download.js

@@ -88,7 +88,7 @@ describe('res', function(){
       var cb = after(2, done);
 
       app.use(function(req, res){
-        res.download('test/fixtures/user.html', 'document', done);
+        res.download('test/fixtures/user.html', 'document', cb)
       });
 
       request(app)