vue/test/unit/features/instance/methods-data.spec.js

import Vue from 'vue'

describe('Instance methods data', () => {
  it('$set/$delete', done => {
    const vm = new Vue({
      template: '<div>{{ a.msg }}</div>',
      data: {
        a: {}
      }
    }).$mount()
    expect(vm.$el.innerHTML).toBe('')
    vm.$set(vm.a, 'msg', 'hello')
    waitForUpdate(() => {
      expect(vm.$el.innerHTML).toBe('hello')
      vm.$delete(vm.a, 'msg')
    }).then(() => {
      expect(vm.$el.innerHTML).toBe('')
    }).then(done)
  })

  describe('$watch', () => {
    let vm, spy
    beforeEach(() => {
      vm = new Vue({
        data: {
          a: {
            b: 1
          }
        }
      })
      spy = jasmine.createSpy('watch')
    })

    it('basic usage', done => {
      vm.$watch('a.b', spy)
      vm.a.b = 2
      waitForUpdate(() => {
        expect(spy.calls.count()).toBe(1)
        expect(spy).toHaveBeenCalledWith(2, 1)
        vm.a = { b: 3 }
      }).then(() => {
        expect(spy.calls.count()).toBe(2)
        expect(spy).toHaveBeenCalledWith(3, 2)
      }).then(done)
    })

    it('immediate', () => {
      vm.$watch('a.b', spy, { immediate: true })
      expect(spy.calls.count()).toBe(1)
      expect(spy).toHaveBeenCalledWith(1)
    })

    it('unwatch', done => {
      const unwatch = vm.$watch('a.b', spy)
      unwatch()
      vm.a.b = 2
      waitForUpdate(() => {
        expect(spy.calls.count()).toBe(0)
      }).then(done)
    })

    it('function watch', done => {
      vm.$watch(function () {
        return this.a.b
      }, spy)
      vm.a.b = 2
      waitForUpdate(() => {
        expect(spy).toHaveBeenCalledWith(2, 1)
      }).then(done)
    })

    it('deep watch', done => {
      var oldA = vm.a
      vm.$watch('a', spy, { deep: true })
      vm.a.b = 2
      waitForUpdate(() => {
        expect(spy).toHaveBeenCalledWith(oldA, oldA)
        vm.a = { b: 3 }
      }).then(() => {
        expect(spy).toHaveBeenCalledWith(vm.a, oldA)
      }).then(done)
    })

    it('warn expresssion', () => {
      vm.$watch('a + b', spy)
      expect('Watcher only accepts simple dot-delimited paths').toHaveBeenWarned()
    })
  })
})