Marble complete not respecting group frames

[iamlothian]

Describe the bug

When I test an observable with a switchMap containing a merge the Marble string passes but the expected completion frame is wrong. '(abcd)|'

Expected behavior

I expected the completion the be on frame 1 not 6 as frame 0 is a group of 4 emissions. '(abcd)|'

Reproduction code

I have the following observable from a NgRx effect

  ActionFactory$ = createEffect(() =>
    this.actions$.pipe(
      ofType(Actions.loadInitialDataSuccess),
      switchMap(() => merge(
          // a number of observables here the subscribe to web sockets each returning different actions
      )),
      catchError((error) => of(Actions.Failure({ error })))
    )
  );

When I test this

// for context
beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [NxModule.forRoot(), MaterialModule],
      providers: [
        provideMockActions(() => actions),
        provideMockStore(),
      ],
    });
    jest.resetAllMocks();
  });

// the test
  it('should subscribe to messages and emit mapped actions', () => {
    testScheduler.run(({ cold, expectObservable }) => {
      actions = cold('a|', {
        a: Actions.loadInitialDataSuccess({ data }),
      });

      expectObservable(effects.FmeActionFactory$).toBe('(abcd)|', {
        a: Actions.actionA({message: ma}),
        b: Actions.actionA({message: mb}),
        c: Actions.actionA({message: mc}),
        d: Actions.actionA({message: md})
      });
    });
  });

I get the following failure

Object {
    -     "frame": 6,
    +     "frame": 1,
          "notification": Object {
            "error": undefined,
            "kind": "C",
            "value": undefined,
          },

Reproduction URL

No response

Version

7.4.0

Environment

Angualr 13, NgRx: 13

Additional context

No response

[kwonoj]

dupe to #5677. for those reason there are 3rd party test library lile rx-sandbox.