Testing a ngrx effect that in one case does not dispatch a new action

Question

I have this one effect where some preconditions have to be true so that a specific action gets dispatched:

@Effect()
prepareLoadDetails$: Observable<Action> = this.actions$
    .ofType(PREPARE_LOAD_DETAILS)
    .withLatestFrom(this.store)
    .filter(([actionType, stateStore]) => this.necessarySelectionsMade(stateStore))
    .map(() => {
        return new LoadDetailsAction();
    });

Now I'm somehow stuck in unit testing this code. There's no problem getting the LoadDetailsAction dispatched. But how can I test that no action is dispatched in the other cases?

describe('prepareLoadDetails$', () => {
    it('should trigger a LoadDetailsAction if all needed selections are made', (done) => {
        // given
        const {runner, effects} = setup({
            // some setup of state here
        });

        // when
        runner.queue(new PrepareLoadDetailsAction());

        // then
        effects.prepareLoadDetails$.subscribe(result => {
            expect(result).toEqual(new LoadDetailsAction());
            done();
        });
    });

    it('should not trigger a LoadDetailsAction if needed selections are not made', (done) => {
        // given
        const {runner, effects} = setup({
            // some other setup of state here
        });

        // when
        runner.queue(new PrepareLoadDetailsAction());

        // then ???
    });
});