gist for medium

setIntervalAmount.js

class MyService {
    constructor(private customInterval = 1000) {
    }

    someMethod() {
        Observable.interval(this.customInterval)
            .subscribe(() => {
                this.logger.logObservable();
            });

        setInterval(() => {
            this.logger.logInterval();
        }, this.customInterval * .5);
    }
}


it('someMethod would be ran with iterator each second', (done) => {
    let myService = new MyService(10);
    myService.someMethod();

    setTimeout(() => {
        expect(logger.logObservable).toHaveBeenCalledTimes(2);
        expect(logger.logInterval).toHaveBeenCalledTimes(1);
        done();
    }, 2 * 10);
});