How to jest promises

promise.test.js

/**
* example how to test promises using jest.
* https://facebook.github.io/jest/docs/en/asynchronous.html#promises
*/

function getPromise() {
  return new Promise(function (success, reject) {
    setTimeout(function() {
      success('job is done');
    }, 200);
  });
}

function getPromiseThatWillReject() {
  return new Promise(function (success, reject) {
    setTimeout(function() {
      reject('job is not done');
    }, 200);
  });
}

it('resolves a promise to assert value', () => {
  return expect(getPromise()).resolves.toEqual('job is done');
});

it('rejects a promise to assert value', () => {
  return expect(getPromiseThatWillReject()).rejects.toEqual('job is not done');
});