用Jest进行Angular MatDialog测试

Question

这里是一个非常简单的Angular组件，我想用Jest测试：

export class EmployeeComponent {

  employees: Employee[] = [];

  constructor(private dialog: MatDialog) {}

  onOpenDialog(): void {
    this.dialog.open(NewEmployeeDialogComponent)
      .afterClosed()
      .pipe(filter(employee => employee))
      .subscribe(employee => this.employees.push(employee));
  }
}

无论我尝试多少，都无法找到模拟open（）和afterClosed（）调用的优雅解决方案。除非，否则我将直接在上面的类中覆盖对话框值，这是糟糕的解决方案。 ：（

describe('EmployeeComponent', () => {

  let component: EmployeeComponent;
  let fixture: ComponentFixture<EmployeeComponent>;
  const mockMatDialog = { open: jest.fn() };

  beforeEach(() => {
    TestBed.configureTestingModule({
      declarations: [EmployeeComponent, NewEmployeeDialogComponent, EmployeeListComponent],
      imports: [
        BrowserAnimationsModule,
        BrowserModule,
        FormsModule,
        HttpClientModule,
        MatDialogModule,
        MatListModule,
        MatSelectModule
      ],
      providers: [{ provide: MatDialog, useValue: mockMatDialog }],
    }).overrideModule(BrowserDynamicTestingModule, {
      set: {
        entryComponents: [NewEmployeeDialogComponent]
      }
    });
  });

  beforeEach(() => {
    fixture = TestBed.createComponent(EmployeeComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });

  it('should create', () => {
    expect(component).toBeTruthy();
  });

  it('should open the dialog and save a valid employee', () => {
    component.dialog = TestBed.get(MatDialog);
    spyOn(TestBed.get(MatDialog), 'open').and.returnValue({afterClosed: () => of(employee)});
    component.openDialog();
    expect(component.employees).toStrictEqual([employee]);
  });
});

您对如何对其进行良好的测试有任何建议吗？