如何在类构造函数中侦测绑定和调用的类方法？

Question

假设我有一个ES6 Target类：

class Target {

  constructor() {
    this.avoidDetection.bind(this) // not sure if necessary
    this.avoidDetection()
  }

  avoidDetection() {
    console.info('Nobody here but us chickens.')
  }
}

...and当avoidDetection方法在构造函数中被调用时，我想要监视该方法，以便：

const targetInstance = new Target() // Nobody here but us chickens.

// `spy` is spying on `avoidDetection`

console.log(spy.called === true) // true

我该怎么做呢？

Answer 1

作为一种特定于React的解决方案，我将普通的ES6 Target类转换为React.Component的子类，以便可以利用酶的instance()方法。结果，我得到了以下工作：

beforeEach(() => {
  targetAvoidDetectionSpy = spyOn(Target.prototype, 'avoidDetection')
  targetWrapper = mount(<Target />)
  targetInstance = targetWrapper.instance()
})

it('is an instance of Target', () => {
  expect(targetInstance).toBeInstanceOf(Target)
})

it('avoids detection (not really)', () => {
  expect(targetAvoidDetectionSpy).toHaveBeenCalled()
})