fix test

test/constructor.test.js

@@ -1,6 +1,6 @@
-var url = 'https://zhw2590582.github.io/assets-cdn/video/one-more-time-one-more-chance-480p.mp4';
-
 describe('Constructor', function() {
+    var url = 'https://zhw2590582.github.io/assets-cdn/video/one-more-time-one-more-chance-480p.mp4';
+
     afterEach(function() {
         [...Artplayer.instances].forEach(art => {
             art.destroy(true);