add scrollTo mock function

Author: huangshuwei

tests/unit/util.js

@@ -1,7 +1,7 @@
 import Vue from "vue";
 
 export function later(delay = 0) {
-    return new Promise(resolve => {
+    return new Promise((resolve) => {
         if (typeof delay === "number") {
             setTimeout(() => {
                 resolve();
@@ -13,3 +13,13 @@ export function later(delay = 0) {
         }
     });
 }
+
+/*
+ * @mockScrollTo
+ * @desc mock scrollTo function
+ */
+export function mockScrollTo() {
+    const fn = jest.fn();
+    Element.prototype.scrollTo = fn;
+    return fn;
+}