<template>
  <view>
    <view :class="class"></view>
    <button @click="start">start</button>
    <button @click="reset">reset</button>
  </view>
</template>

<script>
  export default {
    data() {
      return {
        class: 'box',
      }
    },
    methods: {
      start() {
        this.class = 'box ani'
      },
      reset() {
        this.class = 'box'
      },
      jest_start(){
        this.start()
      },
      jest_reset(){
        this.reset()
      },
    }
  }
</script>

<style>
  .box {
    width: 100px;
    height: 100px;
    background-color: blue;
  }

  .ani {
    transition-duration: 5s;
    width: 200px;
  }
</style>