unit testing - How to mock DialogService.open(...).whenClosed(...) with Jasmine? -

we have typescript code using aurelia framework , dialog plugin trying test jasmine, can't work out how properly.

this source function:

opendialog(action: string) {     this._dialogservice.open({ viewmodel: addaccountwizard })         .whenclosed(result => {             if (!result.wascancelled && result.output) {                 const step = this.steps.find((i) => i.action === action);                 if (step) {                     step.iscompleted = true;                 }             }         }); } 

we can create dialogservice spy, , verify open method - can't work out how make spy invoke whenclosed method mocked result parameter can assert step completed.

this current jasmine code:

it("opens dialog when clicking on incomplete bank account", async done => {     // arrange     arrangememberverificationstatus();     await component.create(bootstrap);     const vm = component.viewmodel gettingstartedcustomelement;     dialogservice.open.and.callfake(() => {         return { whenclosed: () => promise.resolve({})};     });      // act     $(".link, .-arrow")[0].click();      // assert     expect(dialogservice.open).tohavebeencalledwith({ viewmodel: addaccountwizard });     expect(vm.steps[2].iscompleted).tobetruthy(); // fails      done(); }); 

wiki