[new feature] Sidebar: support use v-model to bind active key (#3698)

src/sidebar/test/index.spec.js

@@ -27,6 +27,29 @@ test('click event & change event', () => {
   wrapper.vm.$destroy();
 });
 
+test('v-model', () => {
+  const wrapper = mount({
+    template: `
+      <sidebar v-model="active">
+        <sidebar-item>Text</sidebar-item>
+        <sidebar-item>Text</sidebar-item>
+      </sidebar>
+    `,
+    components: {
+      Sidebar,
+      SidebarItem
+    },
+    data() {
+      return {
+        active: 0
+      };
+    }
+  });
+
+  wrapper.findAll('.van-sidebar-item').at(1).trigger('click');
+  expect(wrapper.vm.active).toEqual(1);
+});
+
 test('without parent', () => {
   const consoleError = console.error;
   try {