Unless I'm misunderstanding something, the resolves and rejects (https://facebook.github.io/jest/docs/expect.html#resolves) won't be available until vNext. What is the recommended way now/in the meantime to test promises with Jest? Is it just putting expects in the thens and catches?
For example:
describe('Fetching', () => {
const filters = {
startDate: '2015-09-01'
};
const api = new TestApiTransport();
it('should reject if no startdate is given', () => {
MyService.fetch().catch(e => expect(e).toBeTruthy()); // see rejects/resolves in v20+
});
it('should return expected data', () => {
MyService.fetch(filters, null, api).then(serviceObjects => {
expect(serviceObjects).toHaveLength(2);
}).catch(e => console.log(e));
});
});
UPDATE 15 June 2019: Not too long after I posted this question, Jest started supporting this out of the box. I changed the accepted answer below to reflect the currently best way to do this.
See Question&Answers more detail:os