message: test: Add a unit test for "$off event and this event added by $once"
diff: @@ -56,6 +56,13 @@ describe('Instance methods events', () => {
  expect(spy).toHaveBeenCalledWith(1, 2, 3)
  })
  + it('$off event added by $once', () => {
  + vm.$once('test', spy)
  + vm.$off('test', spy) // test off event and this event added by once
  + vm.$emit('test', 1, 2, 3)
  + expect(spy).not.toHaveBeenCalled()
  + })
  +
  it('$off', () => {
  vm.$on('test1', spy)
  vm.$on('test2', spy)
  