message: complete eventEmitter unit test
diff: @@ -36,11 +36,17 @@ describe('EventEmitter', () => {
  expect(mockHandler.mock.calls.length).toBe(1)
  })
  - it('should tear down handler when invoking off', () => {
  + it('should tear down handler when invoking off()', () => {
  let mockHandler = jest.fn(x => x + 1)
  eventEmitter.once('test1', mockHandler)
  eventEmitter.off('test1', mockHandler)
  expect(eventEmitter.events.test1.length).toBe(0)
  })
  +
  + it('should register eventTypes when invoking registerType()', () => {
  + eventEmitter.registerType(['test2'])
  +
  + expect(eventEmitter.eventTypes.test2).toBe('test2')
  + })
  })
  