Jasmine/Karma test of cold observables

cold_observable_test.ts

  it('delete me', async (done) => {
    const addAll = nums => nums.reduce((a, b) => a + b, 0);

    const o1 = Observable.of(1);
    const o2 = Observable.of(2).delay(1000).shareReplay(1);

    const o1p2 = Observable.forkJoin([o1, o2]).pipe(
      map(addAll),
      shareReplay(1));

    const o3 = Observable.of(3);

    const o1p2p3 = Observable.forkJoin([o1p2, o3]).pipe(
      map(addAll),
    );

    const val = await o1p2p3.toPromise();
    expect(val).toEqual(6);
    done();
  })