`setup()` is ran twice when used with localVue and @vue/composition-api

[posva]

Steps to reproduce

import { createLocalVue, mount } from '@vue/test-utils'
import VueCompositionAPI, { defineComponent} from '@vue/composition-api'

  it.only('what', async () => {
    const localVue = createLocalVue()
    localVue.use(VueCompositionAPI)
    let n = 0
    const Component = defineComponent({
      render: (h) => h('p'),
      setup() {
        console.log('setup', n++)
      },
    })

    mount(Component, { localVue })
  })

Expected behaviour

One log

Actual behaviour

logs twice and increments n twice

[malopgrics]

I ran in the same bug, have you found any workaround ?

[5HT2]

Nothing new?

[yashhy]

I had the same issue but from the comment vuejs/composition-api#970 seems like VueCompositionAPI is not needed.

My setup before:

import { defineComponent } from '@vue/composition-api'
import { mount } from '@vue/test-utils'
import VueCompositionAPI from '@vue/composition-api'
import { createLocalVue } from '@vue/test-utils'

const localVue = createLocalVue()
localVue.use(VueCompositionAPI)

export async function mountComposition(hookCallback: () => void) {
  const testComponent = defineComponent({
    setup() {
      // setup called twice and so the unMount
      // https://github.com/vuejs/vue-test-utils/issues/1799
      hookCallback()
    },
    render(h) {
      return h('div')
    },
  })

  return await mount(testComponent, { localVue })
}

Now:

import { defineComponent } from '@vue/composition-api'
import { mount } from '@vue/test-utils'
import { createLocalVue } from '@vue/test-utils'

const localVue = createLocalVue()

export async function mountComposition<T>(hookCallback: any): Promise<T> {
  let val: T
  const testComponent = defineComponent({
    setup() {
      val = hookCallback()
    },
    render(h) {
      return h('div')
    },
  })

  await mount(testComponent, { localVue })
  return val
}

From the above setup is called only once and tweaked a bit to return hook's value so we can assert it better.