gist for medium

realInterval.test.js

it('someMethod would be ran with iterator each second', (done) => {
  myService.someMethod();
  
  setTimeout(() => {
            expect(logger.logObservable).toHaveBeenCalledTimes(2);
            expect(logger.logInterval).toHaveBeenCalledTimes(1);
            done();
        }, 2 * 1000);
});