[英]Angular Unit Tests using TestBed.inject succeed/fail according to tests execution order
我有一個使用 Jest 進行單元測試的 angular 應用程序(v11.1.0)。
我使用TestBed.inject
來獲取單個測試中的服務實例並 spyOn 他們的方法進行測試,或者他們已被調用或 mocking 返回值。
但是切換到 Typescript strict
模式后,測試失敗。 但是如果我改變一些測試的順序,一切都會順利進行。 似乎模擬的服務仍然在不同的單元測試之間進行交互。
我嘗試使用jest.resetAllMocks()
,但它也沒有解決問題。 在我使用的代碼下方:
單元測試
describe('AppComponent', () => {
let component: AppComponent;
let fixture: ComponentFixture<AppComponent>;
beforeEach(
waitForAsync(() => {
TestBed.configureTestingModule({
imports: [
RouterTestingModule,
HttpClientTestingModule,
TranslateModule.forRoot(),
],
declarations: [AppComponent],
providers: [
{ provide: InformationService, useValue: informationServiceMock }
],
}).compileComponents();
})
);
beforeEach(() => {
fixture = TestBed.createComponent(AppComponent);
component = fixture.componentInstance;
});
describe('Test set', () => {
it(`should have default text`, () => {
fixture.detectChanges();
expect(component.maintenanceBannerMessage).toBe('BANNER DE');
expect(component.maintenanceBannerTitle).toBe('TITLE DE');
});
it(`Should open function`, () => {
const dialog = TestBed.inject(MatDialog);
const informationService = TestBed.inject(InformationService);
jest.spyOn(informationService, 'updateOverlayAction');
jest.spyOn(dialog, 'open');
fixture.detectChanges();
expect(dialog.open).toHaveBeenCalled();
expect(informationService.updateOverlayAction).toHaveBeenCalled();
});
//------------------------------------------------------------
// If I move this test in 2. position, the test `Should open function` FAILS
// as getAnnouncementsByType keeps returning null instead of getting it from the
// informationServiceMock provided in the configureTestingModule
it(`should not be showed`, () => {
const informationService = TestBed.inject(InformationService);
jest
.spyOn(informationService, 'getAnnouncementsByType')
.mockReturnValue(of(null as any));
fixture.detectChanges();
expect(component.maintenanceBannerMessage).toBeUndefined();
expect(component.maintenanceBannerTitle).toBeUndefined();
});
//------------------------------------------------------------
it(`should not be showed`, () => {
const dialog = TestBed.inject(MatDialog);
const informationService = TestBed.inject(InformationService);
jest
.spyOn(informationService, 'getAnnouncementsByType')
.mockReturnValue(of(null as any));
jest.spyOn(dialog, 'open');
fixture.detectChanges();
expect(dialog.open).not.toHaveBeenCalled();
});
});
});
服務模擬
export const announcementsMockData = [
{
announcementId: '6000',
type: AnnouncementType.BANNER,
text: { de: 'BANNER DE', fr: 'BANNER FR', it: 'BANNER IT', en: 'BANNER EN' },
title: { de: 'TITLE DE', fr: 'TITLE FR', it: 'TITLE IT', en: 'TITLE EN' }
}, {
announcementId: '6100',
type: AnnouncementType.OVERLAY,
text: { de: 'OVERLAY DE', fr: 'OVERLAY FR', it: 'OVERLAY IT', en: 'OVERLAY EN' },
title: { de: 'OVERLAY DE', fr: 'OVERLAY FR', it: 'OVERLAY IT', en: 'OVERLAY EN' },
_links: { create: { href: '/announcements/6100/actions' } }
}
];
export const informationServiceMock = {
getAnnouncementsByType: (type: AnnouncementType) => {
return announcementsMockData.map(a => new Announcement(a)).filter(a => a.type === type);
},
updateOverlayAction: (link: ResourceLink, action: OverlayAction) => of(null),
};
應用組件
this.informationService.getAnnouncementsByType(AnnouncementType.BANNER)
.pipe(takeUntil(this.destroy$))
.subscribe(([currentLanguage, banners]) => {
if (banners?.length > 0) {
if (banners[0].title) {
this.maintenanceBannerTitle = banners[0].title[currentLanguage.key as keyof LanguageObject];
}
if (banners[0].text) {
this.maintenanceBannerMessage =
banners[0].text[currentLanguage.key as keyof LanguageObject];
}
}
});
測試特定的間諜應該恢復到所有測試通用的一些實現,不這樣做會導致測試交叉污染,因為測試會影響后續測試。
jest.resetAllMocks()
提供了不良行為,應該完全避免。 在beforeEach
中使用時,它會毫無例外地重置所有間諜的實現並使它們成為存根。 在測試中使用時,這也會導致測試交叉污染。 如果需要重置特定的間諜實現,可以使用mockReset()
來完成。
根據經驗, jest.restoreAllMocks()
應該在beforeEach
中使用,它會將使用jest.spyOn
創建的所有間諜恢復到原始實現,以防萬一。 這種行為通常適用於所有測試,因此可以在 Jest 配置中啟用它。
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