Seems to be expected as the .lazy modifier only updates myProperty on the change event, but setting the value of the textarea like that is like typing in it and therefore triggers an input event (which the non-lazy v-model would listen for).

Try calling blur() on the element after setting the value, that should trigger the change event.

Hi @LinusBorg

Thank you for your quick reply. I had already tried you proposal and it doesn't work. Same result. The watched property is not executed.
I've even tried to remove .lazy modifier but the result is the same.

I think this is just jest succing at simulating the change event.

Try https://vue-test-utils.vuejs.org/api/wrapper/#trigger

I didn't clarify it in my previous post.
I tried using trigger('blur') and it didn't work out.

We actually cover this case explicitly by checking for lazy and doing change:

Did you forget to declare myProperty in your real code, or just your repro?

Anyway, this is working fine for me (including setValue('')). Does this help?

Component:

<template>
  <div>
    <textarea id="labeling-text" v-model.lazy="myProperty"></textarea>
  </div>
</template>

<script>
export default {
  data() {
    return {
      myProperty: 'ok'
    }
  },
  watch: {
    myProperty() {
      this.$emit('myEvent', this.myProperty)
    }
  }
}
</script>

Test:

import { mount } from '@vue/test-utils'
import HelloWorld from '@/components/HelloWorld.vue'

it('Raises an event when textarea changes', async () => {
  const wrapper = mount(HelloWorld)
  const $ta = wrapper.find('#labeling-text')
  await $ta.setValue('OK!!!')
  console.log(wrapper.emitted('myEvent')) // => [ [ 'OK!!!' ] ]
})

I just forgot to include the property in the repro. Sorry!
What version of vuejs are you using right now?

I just created a new project using the Vue CLI and chose 2.x when I was trying to reproduce this issue. Should be using the latest version of 2.x.

If you are using Vue 3, you will need v2 of this library (which you can get with yarn add @vue/test-utils@next, or creating a new project with the Vue CLI).

Are you still having this problem? The code above was working for me. Maybe you can post a repository with the bug so I can reproduce it?