Need to reassign stubbed component with findComponent after update to 2.0.0-rc.10

[freakzlike]

I am currently having the issue, that some of my tests fail after updating from 2.0.0-rc.9 to 2.0.0-rc.10. When manually stubbing a component then I need to reassign the wrapper with findComponent to receive the correct values after making any update (e.g. emits or setProps).

After some checking I created a code snippet to test with. If you run the snippet with 2.0.0-rc.9 the tests passes. If running with 2.0.0-rc.10 the test "should test with stub" fails. In comparision with "should test with stub and reassign" there is only the reassign child = wrapper.findComponent({ name: 'ChildComponent' }) missing which is not necessary when testing without manually stub or with 2.0.0-rc.9.

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

const ChildComponent = defineComponent({
  name: 'ChildComponent',
  props: {
    modelValue: {
      type: String,
      required: true
    }
  },
  template: '<span>{{ modelValue }}</span>'
})

const MainComponent = defineComponent({
  components: { ChildComponent },
  props: {
    modelValue: {
      type: String,
      required: true
    }
  },
  template: '<ChildComponent v-model="modelValue" />'
})

describe('test stub', () => {
  it('should test without stub', async () => {
    const wrapper = mount(MainComponent, {
      props: { modelValue: '1' }
    })

    const child = wrapper.findComponent({ name: 'ChildComponent' })
    expect(child.props('modelValue')).toBe('1')

    await wrapper.setProps({ modelValue: '2' })

    expect(child.props('modelValue')).toBe('2')
  })

  /**
   * Test stub component with reassign wrapper with findComponent
   * Works with rc.9 and rc.10
   */
  it('should test with stub and reassign', async () => {
    const wrapper = mount(MainComponent, {
      props: { modelValue: '1' },
      global: {
        stubs: {
          ChildComponent
        }
      }
    })

    let child = wrapper.findComponent({ name: 'ChildComponent' })
    expect(child.props('modelValue')).toBe('1')

    await wrapper.setProps({ modelValue: '2' })

    child = wrapper.findComponent({ name: 'ChildComponent' })
    expect(child.props('modelValue')).toBe('2')
  })

  /**
   * Test stub component without reassign wrapper with findComponent
   * Works with rc.9. Fails with rc.10
   */
  it('should test with stub', async () => {
    const wrapper = mount(MainComponent, {
      props: { modelValue: '1' },
      global: {
        stubs: {
          ChildComponent
        }
      }
    })

    const child = wrapper.findComponent({ name: 'ChildComponent' })
    expect(child.props('modelValue')).toBe('1')

    await wrapper.setProps({ modelValue: '2' })

    expect(child.props('modelValue')).toBe('2')
  })
})

[cexbrayat]

Hi @freakzlike thanks for the detailed report

rc.10 included a lot of work around stubs from @xanf

@xanf was this intended or do you think it is a regression?

[lmiller1990]

If you pass ChildComponent to components instead of stubs does it work?

As an aside, what exactly is the goal here? What is the use case to test if v-model works with a stubbed component? I understand this is a minimal reproduction, I'm not sure what the real world parallel for this use case is. I am still interesting in finding out if this change was intentional or not.

Hard to say which is "correct", since this is not something you can do in a real app, so I suppose we should match whatever VTU v1 does.

[xanf]

@freakzlike Thank you for catching that

@lmiller1990 @cexbrayat This was unintended regression, I've created #813 to fix that and explained root cause of the issue