测试构造函数使用Sinon调用方法

Question

I'd like to ensure that the constructor is calling a method when instantiated with Sinon, however, I can't seem to get this to work, as I believe the sinon is not watching the correct instantiation:

class Test {
  constructor() {
    this.someFunction();
  }

  someFunction() {
    return 1;
  }
}

... and the test

describe('constructor', () => {

  it('should call someFunction()', () => {
    const spyFunc = new Spy(new Test(), 'someFunction');
    expect(spyFunc.calledOnce).to.be.true;
  });

});

Answer 1

Try to spy to Test.prototype.someFunction before invoking constructor. Something like this

sinon.spy(Test.prototype, 'someFunction')
const spyFunc = new Test();
expect(spyFunc.someFunction.calledOnce).to.be.true;