feat(CountDown): add change event (#5599)

src/count-down/README.md

@@ -130,6 +130,7 @@ export default {
 | Event | Description | Arguments |
 |------|------|------|
 | finish | Triggered when count down finished | - |
+| change `2.4.4` | Triggered when count down changed | timeData |
 
 ### Slots
 

src/count-down/README.zh-CN.md

@@ -140,6 +140,7 @@ export default {
 | 事件名 | 说明 | 回调参数 |
 |------|------|------|
 | finish | 倒计时结束时触发 | - |
+| change `2.4.4` | 倒计时变化时触发 | timeData |
 
 ### Slots
 

src/count-down/index.js

@@ -141,6 +141,7 @@ export default createComponent({
 
     setRemain(remain) {
       this.remain = remain;
+      this.$emit('change', this.timeData);
 
       if (remain === 0) {
         this.pause();

src/count-down/test/index.spec.js

@@ -213,3 +213,21 @@ test('pause when deactivated', async () => {
   wrapper.setData({ render: true });
   expect(countDown.counting).toBeFalsy();
 });
+
+test('change event', async () => {
+  const wrapper = mount(CountDown, {
+    propsData: {
+      time: 1,
+    },
+  });
+
+  expect(wrapper.emitted('change')).toBeFalsy();
+  await later(50);
+  expect(wrapper.emitted('change')[0][0]).toEqual({
+    days: 0,
+    hours: 0,
+    milliseconds: 0,
+    minutes: 0,
+    seconds: 0,
+  });
+});