test(e2e): add e2e test for commits example (#526)

* test(e2e): add e2e test for commits example

* test(e2e): add waitForResponse to enhance the test

* test(e2e): use mocks for commits test

packages/vue/examples/classic/commits.html

@@ -1,4 +1,5 @@
 <script src="../../dist/vue.global.js"></script>
+<script src="../mocks/commits.js"></script>
 
 <div id="demo">
   <h1>Latest Vue.js Commits</h1>
@@ -41,11 +42,18 @@ const App = {
 
   methods: {
     fetchData() {
-      fetch(`${API_URL}${this.currentBranch}`)
-        .then(res => res.json())
-        .then(data => {
-          this.commits = data
-        })
+      if (window.location.hash === '#test') {
+        // use mocks in e2e to avoid dependency on network / authentication
+        setTimeout(() => {
+          this.commits = window.MOCKS[this.currentBranch]
+        }, 0)
+      } else {
+        fetch(`${API_URL}${this.currentBranch}`)
+          .then(res => res.json())
+          .then(data => {
+            this.commits = data
+          })
+      }
     },
     truncate(v) {
       const newline = v.indexOf('\n')