vue/test/unit/specs/api/events_spec.js

var Vue = require('../../../../src/vue')

describe('Events API', function () {

  var vm, spy
  beforeEach(function () {
    vm = new Vue()
    spy = jasmine.createSpy('emitter')
  })
  
  it('$on', function () {
    vm.$on('test', function () {
      // expect correct context
      expect(this).toBe(vm)
      spy.apply(this, arguments)
    })
    vm.$emit('test', 1, 2 ,3, 4)
    expect(spy.calls.count()).toBe(1)
    expect(spy).toHaveBeenCalledWith(1, 2, 3, 4)
  })

  it('$once', function () {
    vm.$once('test', spy)
    vm.$emit('test', 1, 2 ,3)
    vm.$emit('test', 2, 3, 4)
    expect(spy.calls.count()).toBe(1)
    expect(spy).toHaveBeenCalledWith(1, 2, 3)
  })

  it('$off', function () {
    vm.$on('test1', spy)
    vm.$on('test2', spy)
    vm.$off()
    vm.$emit('test1')
    vm.$emit('test2')
    expect(spy).not.toHaveBeenCalled()
  })

  it('$off event', function () {
    vm.$on('test1', spy)
    vm.$on('test2', spy)
    vm.$off('test1')
    vm.$off('test1') // test off something that's already off
    vm.$emit('test1', 1)
    vm.$emit('test2', 2)
    expect(spy.calls.count()).toBe(1)
    expect(spy).toHaveBeenCalledWith(2)
  })

  it('$off event + fn', function () {
    var spy2 = jasmine.createSpy('emitter')
    vm.$on('test', spy)
    vm.$on('test', spy2)
    vm.$off('test', spy)
    vm.$emit('test', 1, 2, 3)
    expect(spy).not.toHaveBeenCalled()
    expect(spy2.calls.count()).toBe(1)
    expect(spy2).toHaveBeenCalledWith(1, 2, 3)
  })

  it('$broadcast', function () {
    var child1 = vm.$addChild()
    var child2 = vm.$addChild()
    var child3 = child1.$addChild()
    child1.$on('test', spy)
    child2.$on('test', spy)
    child3.$on('test', spy)
    vm.$broadcast('test')
    expect(spy.calls.count()).toBe(3)
  })

  it('$broadcast optimization', function () {
    var child = vm.$addChild()
    var child2 = child.$addChild()
    // hooks should not incurr the bookkeeping cost
    child.$on('hook:created', function () {})
    expect(vm._eventsCount['hook:created']).toBeUndefined()
    child.$on('test', spy)
    expect(vm._eventsCount['test']).toBe(1)
    // child2's $emit & $broadcast
    // shouldn't get called if no child listens to the event
    child2.$emit = spy
    child2.$broadcast = spy
    vm.$broadcast('test')
    expect(spy.calls.count()).toBe(1)
  })

  it('$broadcast cancel', function () {
    var child = vm.$addChild()
    var child2 = child.$addChild()
    child.$on('test', function () {
      return false
    })
    child2.$on('test', spy)
    vm.$broadcast('test')
    expect(spy).not.toHaveBeenCalled()
  })

  it('$dispatch', function () {
    var child = vm.$addChild()
    var child2 = child.$addChild()
    child.$on('test', spy)
    vm.$on('test', spy)
    child2.$dispatch('test')
    expect(spy.calls.count()).toBe(2)
  })

  it('$dispatch cancel', function () {
    var child = vm.$addChild()
    var child2 = child.$addChild()
    child.$on('test', function () {
      return false
    })
    vm.$on('test', spy)
    child2.$dispatch('test')
    expect(spy).not.toHaveBeenCalled()
  })

})