fix: spy on wrapper.vm with Jest

src/mount.ts

@@ -441,8 +441,11 @@ export function mount(
  // if not, use the return value from app.mount.
  const appRef = vm.$refs[MOUNT_COMPONENT_REF] as ComponentPublicInstance
  const $vm = Reflect.ownKeys(appRef).length ? appRef : vm
+ // we add `hasOwnProperty` so jest can spy on the proxied vm without throwing
+ $vm.hasOwnProperty = (property) => {
+ return Reflect.has($vm, property)
+ }
  console.warn = warnSave
-
  return createWrapper(app, $vm, setProps)
 }
 

tests/vm.spec.ts

@@ -24,4 +24,25 @@ describe('vm', () => {
 
  expect(wrapper.vm.isEnabled).toBe(false)
  })
+
+ it('allows spying on vm', async () => {
+ const Component = defineComponent({
+ name: 'VTUComponent',
+ template: '<div @click="toggle()">{{ msg }}</div>',
+ setup() {
+ const msg = 'hello'
+ const isEnabled = ref(true)
+ const toggle = () => (isEnabled.value = !isEnabled.value)
+ return { msg, isEnabled, toggle }
+ }
+ })
+
+ const wrapper = mount(Component)
+
+ jest.spyOn(wrapper.vm, 'toggle')
+
+ await wrapper.get('div').trigger('click')
+
+ expect(wrapper.vm.toggle).toHaveBeenCalled()
+ })
 })