带有解雇动作的自定义小吃店的单元测试

Question

我已经定义了许多不同的方法来打开海关小吃店，有和没有持续时间，有和没有解雇事件，例如：

showError(title: string, message: string): void {
    this.zone.run(() => {
      this.snackBar.openFromComponent(NotificationSnackbarComponent, {
        duration: 3000,
        data: {
          title,
          message,
          snackType: 'error',
          closeSnackbar: () => {
            this.snackBar.dismiss();
          },
        },
      });
    });
  }

我怎样才能对这个事件进行单元测试：

closeSnackbar: () => {   this.snackBar.dismiss(); },

我尝试过这种方法：

it('should show notification smackbar from showError', () => {
    const spy = spyOn(snackBar, 'openFromComponent');
    const snackBarSpy = spyOn(snackBar, 'dismiss');
    service.showError('Title', 'Message');
    expect(spy).toHaveBeenCalled();
    snackBar.dismiss();
    expect(snackBarSpy).toHaveBeenCalled()
  });

但我需要测试closeSnackbar 而不是dismiss。我不知道如何才能访问该方法。我在每个配置之前都有这个：

let service: NotificationService;
let snackBar: MatSnackBar;

beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [
        MatSnackBarModule
      ],
      providers: [
        { provide: MatSnackBarRef, useValue: {} },
        { provide: MAT_SNACK_BAR_DATA, useValue: {} },
      ]
    });
    service = TestBed.inject(NotificationService);
    snackBar = TestBed.inject(MatSnackBar);
});

有什么想法吗？谢谢。

Answer 1

试试下面的方法，我添加了 cmets。希望你能跟随并理解。

let service: NotificationService;
  let snackBar: MatSnackBar;
  let mockSnackBarRef: jasmine.SpyObj<MatSnackBarRef>;

  beforeEach(() => {
    // the first string ('SnackBarRef') is used for debugging purposes
    // the second array of strings are public methods you would like to mock
    mockSnackBarRef = jasmine.createSpyObj<MatSnackBarRef>('SnackBarRef', ['openFromComponent', 'dismiss']);
    TestBed.configureTestingModule({
      imports: [
        MatSnackBarModule
      ],
      providers: [
        // change it to provide the mock - I assume this.snackBar is
        // MatSnackBarRef
        { provide: MatSnackBarRef, useValue: mockSnackBarRef },
        { provide: MAT_SNACK_BAR_DATA, useValue: {} },
      ]
    });
    service = TestBed.inject(NotificationService);
    snackBar = TestBed.inject(MatSnackBar);
  });

....
it('should show notification smackbar from showError', () => {
    service.showError('Title', 'Message');
    // expect method to be called
    expect(mockSnackBarRef.openFromComponent).toHaveBeenCalled();
    // get the 2nd argument of the most recent call of openFromComponent
    const secondArgument = mockSnackBarRef.openFromComponent.calls.mostRecent().args[1];
    // call the closeSnackbar
    secondArgument.data.closeSnackbar();
    // expect the dismiss to be called
    expect(mockSnackBarRef.dismiss).toHaveBeenCalled();
  });