How do I stub a chain of methods in Sinon?

Question

I know how to use stub to replace one function.

sandbox.stub(Cars, "findOne",
            () => {return car1 });

But now I have a line in my function I want to test that I need to stub that looks like this

Cars.find().fetch()

So there is a chain of function here and I'm unsure what I need to do. How do I stub "find" to return something that I can use to stub "fetch"?

Answer 1

IMHO, we can just use returns to do this. We don't need to use callsFake or mock it as function.

// Cars.find().fetch()

sinon.stub(Cars, 'find').returns({
  fetch: sinon.stub().returns(anything);
});

in case, if there is another method after fetch(), we can use returnsThis()

// Cars.find().fetch().where()

sinon.stub(Cars, 'find').returns({
  fetch: sinon.stub().returnsThis(),
  where: sinon.stub().returns(anything);
});

Ref: https://sinonjs.org/releases/v6.3.3/

Hope it helps

Answer 2

Try this:

sandbox.stub(Cars, "find", () => {
    return {
        fetch: sinon.stub().returns(anything);
    };
});