test(throttle): should not leak ChildSubscriptions (ReactiveX#2355)

spec/operators/throttle-spec.ts

@@ -337,4 +337,25 @@ describe('Observable.prototype.throttle', () => {
  }
  );
  });
+
+ it('should not leak when child completes before next source emit', () => {
+ const oStream = new Rx.Subject<number>();
+ let iStream: Rx.Subject<number>;
+ const aStream = oStream.throttle(() => {
+ return (iStream = new Rx.Subject<number>());
+ });
+ const result = [];
+ let sub = aStream.subscribe((x: number) => result.push(x));
+
+ [0, 1, 2, 3, 4].forEach((n) => {
+ oStream.next(n); // creates inner
+ iStream.complete(); // throttle will unsubscribe iStream here.
+ });
+ expect(result).to.deep.equal([0, 1, 2, 3, 4]);
+ // Expect one child of switch(): The oStream
+ expect(
+ (<any>sub)._subscriptions[0]._innerSub._subscriptions.length
+ ).to.equal(1);
+ sub.unsubscribe();
+ });
 });