core/packages/runtime-core/__tests__/misc.spec.ts

import { h, isReactive, nodeOps, reactive, render } from '@vue/runtime-test'

describe('misc', () => {
  test('component public instance should not be observable', () => {
    let instance: any
    const Comp = {
      render() {},
      mounted() {
        instance = this
      },
    }
    render(h(Comp), nodeOps.createElement('div'))
    expect(instance).toBeDefined()
    const r = reactive(instance)
    expect(r).toBe(instance)
    expect(isReactive(r)).toBe(false)
  })
})