Unit test mongoose promises with sinon - node.js

Question

I am trying to unit test a mongoose object that uses promises. I have written the test below and it works but it's not complete. I can't figure out how to test if the 'then' or 'catch' methods are called.
How can I use a spy to check that the 'then' method is called when I resolve the promise?
Method to test
export function create(req, res) {
User
.createAsync(req.body)
.then(handleCreate(res, req.originalUrl))
.catch(handleError(res));
}
Unit test
it('should do something', () => {
const req = {
body: 45,
};
const res = {};
const mockRole = sandbox.mock(Role).expects('createAsync').once().withArgs(45)
.returns(Promise.resolve());
controller.create(req, res);
});
UPDATE WITH SOLUTION I USED (May 6th, 2016)
Thanks #ReedD for helping me in the right direction
Although this "works", I feel like I'm testing the functionality of promises more than my code.
it('should call create with args and resolve the promise', () => {
const createSpy = sinon.spy();
const errorSpy = sinon.spy();
sandbox.stub(responses, 'responseForCreate').returns(createSpy);
sandbox.stub(responses, 'handleError').returns(errorSpy);
sandbox.mock(Role).expects('createAsync').once().withArgs(45)
.returns(Promise.resolve());
return controller.create(req, res).then(() => {
expect(createSpy.calledOnce).to.be.equal(true);
expect(errorSpy.calledOnce).to.be.equal(false);
});
});

Answer 1

You could add handleCreate and handleError to module.exports and then make stubs or spys of those. Below is an example of what I think you're trying to do. I also assumed you were using sinon/chai.
http://ricostacruz.com/cheatsheets/sinon-chai.html
// controller.js
module.exports = {
handleCreate: function () {
// ..code
},
handleError: function () {
// ..code
},
create: function (req, res) {
User
.createAsync(req.body)
.then(this.handleCreate(res, req.originalUrl))
.catch(this.handleError(res));
}
};
// test/test.js
var controller = require('../controller');
it('should do something', function (done) {
var handleCreate = sandbox.spy(controller, 'handleCreate');
var handleError = sandbox.spy(controller, 'handleError');
var mockRole = sandbox
.mock(Role)
.expects('createAsync')
.once().withArgs(45)
.returns(Promise.resolve());
var req = {
body: 45,
};
var res = {
send: function () {
expect(handleCreate).to.be.calledOnce;
expect(handleError).to.not.be.called;
done();
}
};
controller.create(req, res);
});