NGRX jest-marbles Testing Effect Involving forkJoin Operator - unit-testing

Question

Unit Testing an Effect that Incorporates a forkJoin Operator
I have an Angular 15 project using NGRX. I'm writing unit tests against my store and associated modules.
My effect basically works like a polling service and calls a service inside a forkJoin operator. The code is below.
getGroupFlow$ = createEffect(() =>
this.actions$.pipe(
ofType(StatusPollingActions.pollFlow),
tap(() => this.continuePolling = true),
withLatestFrom(of(environment.statusPollingInterval)),
switchMap(([action, pollingInterval]) =>
timer(0, pollingInterval).pipe(
takeWhile(() => this.continuePolling, true),
switchMap(() =>
forkJoin([
this.nifiService.getProcessGroupFlow(this.inputGroupId),
this.nifiService.getProcessGroupFlow(this.processingGroupId),
this.nifiService.getProcessGroupFlow(this.outputGroupId),
this.nifiService.getConnectionsForGroup(this.mainCanvasId),
]).pipe(
map(([incoming, processing, outgoing, groupConnections]) =>
StatusPollingActions.pollFlowSuccess({
incomingGroupFlow: incoming,
processingGroupFlow: processing,
outputGroupFlow: outgoing,
groupConnections: groupConnections,
})
),
catchError((error) =>
of(StatusPollingActions.pollFlowFailure({ error }))
)
)
)
)
)
)
);
Of note... the variables referenced in the effect are defined below:
continuePolling: boolean variable scoped to the class
statusPollingInterval: number indicating how frequently to poll (passed in from environment)
I'm a bit new to writing tests against NGRX and I'm using jest and jest-marbles for my test cases.
I need help building out the test case to model the expected flow and output.
Any help would be greatly appreciated!