updated unit tests to make sure updated is called

Author: samaneh-kazemi

packages/model-viewer/src/extra-model.ts

@@ -44,7 +44,7 @@ export class ExtraModelElement extends ReactiveElement {
     super.updated(changedProperties);
     console.log('updated is called');
     if (changedProperties.has('src')) {
-      this.loaded = false;
+      this.loaded = true;
       console.log('src has changed');
     }
     if (changedProperties.has('availableVariants')) {

packages/model-viewer/src/test/extra-model-spec.ts

@@ -40,9 +40,10 @@ suite('ExtraModelElement', () => {
   });
 
   suite('with src property', () => {
-    test('set loaded to false at first when src is set', async () => {
+    test('set loaded to true at first when src is set', async () => {
       extraElement.src = assetPath('models/Astronaut.glb');
-      expect(extraElement.loaded).to.be.false;
+      await extraElement.updateComplete;
+      expect(extraElement.loaded).to.be.true;
     });
     test.skip('dispatches a load event when src is set', async () => {
       const sourceLoads = waitForEvent(extraElement, 'load');