[Improvement] Rebuild test system (#1051)

packages/tree-select/test/index.spec.js

@@ -0,0 +1,27 @@
+import TreeSelect from '../';
+import demoTest from '../../../test/demo-test';
+import { mount } from '@vue/test-utils';
+
+demoTest(TreeSelect);
+
+test('empty list', () => {
+  expect(mount(TreeSelect).html()).toMatchSnapshot();
+});
+
+test('select item', () => {
+  const item = {
+    text: 'city1',
+    id: 1
+  };
+  const wrapper = mount(TreeSelect, {
+    propsData: {
+      items: [{
+        text: 'group1',
+        children: [item]
+      }]
+    }
+  });
+
+  wrapper.find('.van-tree-select__item').trigger('click');
+  expect(wrapper.emitted('itemclick')[0][0]).toEqual(item);
+});