[Improvement] Switch: add test cases (#1202)

packages/switch-cell/test/index.spec.js

@@ -0,0 +1,13 @@
+import SwitchCell from '..';
+import { mount } from '@vue/test-utils';
+
+test('emit event', () => {
+  const wrapper = mount(SwitchCell);
+
+  wrapper.vm.$on('input', value => {
+    wrapper.setProps({ value });
+  });
+  wrapper.find('.van-switch').trigger('click');
+
+  expect(wrapper.emitted('change')).toBeTruthy();
+});