Sinonjs消耗诺言的测试方法

Question

I have a javascript method that looks something like this:

someMethod=function(){
  somePromise.run().then(()=>{
    //do success stuff
  }).catch((err)=>{
    //do fail stuff
    registerError(err);
  });
}

I want to make sure that the error is getting registered, so I've set up the following test.

it('should register error', ()=>{
  somePromise = {
    run: sinon.stub
  };
  registerError = sinon.stub;
  somePromise.returns(Promise.reject({err: 'foo'}));
  someMethod();
  assert(registerError.calledWith({err: 'foo'}));
});

This test fails because the assert fires before the promises in someMethod finish. I could update someMethod to return a promise, but that smells fishy to me. Any input is welcome, thanks!

Answer 1

You have created an async method that does not return either a promise or contain a callback as an argument. This is not a good practice as you cannot know when your async function will finish. A simple fix is to return the promise from the function and perform your assert as a part of the promise chain.