vue/test/unit/features/options/extends.spec.js

import Vue from 'vue'

describe('Options extends', () => {
  it('should work on objects', () => {
    const A = {
      data () {
        return { a: 1 }
      }
    }
    const B = {
      extends: A,
      data () {
        return { b: 2 }
      }
    }
    const vm = new Vue({
      extends: B,
      data: {
        c: 3
      }
    })
    expect(vm.a).toBe(1)
    expect(vm.b).toBe(2)
    expect(vm.c).toBe(3)
  })

  it('should work on extended constructors', () => {
    const A = Vue.extend({
      data () {
        return { a: 1 }
      }
    })
    const B = Vue.extend({
      extends: A,
      data () {
        return { b: 2 }
      }
    })
    const vm = new Vue({
      extends: B,
      data: {
        c: 3
      }
    })
    expect(vm.a).toBe(1)
    expect(vm.b).toBe(2)
    expect(vm.c).toBe(3)
  })

  it('should work with global mixins + Object.prototype.watch', done => {
    let fakeWatch = false
    if (!Object.prototype.watch) {
      fakeWatch = true
      // eslint-disable-next-line no-extend-native
      Object.defineProperty(Object.prototype, 'watch', {
        writable: true,
        configurable: true,
        enumerable: false,
        value: () => {}
      })
    }

    Vue.mixin({})

    const spy = jasmine.createSpy('watch')
    const A = Vue.extend({
      data: function () {
        return { a: 1 }
      },
      watch: {
        a: spy
      },
      created: function () {
        this.a = 2
      }
    })
    new Vue({
      extends: A
    })
    waitForUpdate(() => {
      expect(spy).toHaveBeenCalledWith(2, 1)

      if (fakeWatch) {
        delete Object.prototype.watch
      }
    }).then(done)
  })
})