title: How do I get TestScheduler to tick in RxJs5?
body: <p>I'm trying to write a sample unit test with <code>Observable.interval</code> in RxJs version 5. I'm running the following code, but my observable only fires once, not 20 times, as anticipated.</p>
  
  <pre><code>it('does its interval thing synchonously', ()=&gt; {
  
          let x = [];
          let scheduler = new Rx.TestScheduler();
          let interval$ = Rx.Observable.interval(500, scheduler).take(20);
  
          interval$.subscribe(
              value =&gt; {
                  x.push(value);
                  console.log(value)
              },
          );
  
          for(let i = 0; i &lt; 20; i++) {
              scheduler.flush();
          }
  
          expect(x.length).toBe(20);
  
      });
  </code></pre>
  
  <p>How do I make my <code>TestScheduler</code> move the Observable forward by 10000 milliseconds?</p>