perf(select): select options watch flush post (#1513)

* perf(select): select options watch flush post

fix #1512

* test(select): cover sync set value and options test

Co-authored-by: liao-zhi-peng <liaozhipeng@weis-inc.com>

packages/carousel/__tests__/carousel.spec.ts

@@ -210,6 +210,7 @@ describe('Carousel', () => {
     await nextTick()
     await wrapper.find('.el-carousel').trigger('mouseenter')
     const items = wrapper.vm.$el.querySelectorAll('.el-carousel__item')
+    await nextTick()
     await wait(60)
     expect(items[1].classList.contains('is-active')).toBeTruthy()
     done()

packages/select/__tests__/select.spec.ts

@@ -164,6 +164,38 @@ describe('Select', () => {
     expect(wrapper.find('.el-input__inner').element.value).toBe('双皮奶')
   })
 
+
+  test('sync set value and options', async () => {
+    const wrapper = _mount(`
+    <el-select v-model="value">
+      <el-option
+        v-for="item in options"
+        :label="item.label"
+        :key="item.value"
+        :value="item.value">
+      </el-option>
+    </el-select>
+  `,
+    () => ({
+      options: [{
+        value: '选项1',
+        label: '黄金糕',
+      }, {
+        value: '选项2',
+        label: '双皮奶',
+      }],
+      value: '选项2',
+    }))
+    const vm = wrapper.vm as any
+    vm.options = [{
+      value: '选项1',
+      label: '黄金糕',
+    }]
+    vm.value = '选项1'
+    await wrapper.vm.$nextTick()
+    expect(wrapper.find('.el-input__inner').element.value).toBe('黄金糕')
+  })
+
   test('single select', async () => {
     const wrapper = _mount(`
       <el-select v-model="value" @change="handleChange">

packages/select/src/useSelect.ts

@@ -230,6 +230,9 @@ export const useSelect = (props, states: States, ctx) => {
         checkDefaultFirstOption()
       }
     },
+    {
+      flush: 'post',
+    },
   )
 
   watch(() => states.hoverIndex, val => {