Jest mock extension

Mock a class

This would be useful in Angular and NestJS testing.

Plain class test:

const SampleServiceMockClass: Type<ClassMock<SampleService>> = mockClass(SampleService);
const sampleServiceMock: ClassMock<SampleService> = new SampleServiceMockClass();

Angular test:

let cookieService: ClassMock<CookieService>;

beforeEach(async () => {
    TestBed.configureTestingModule({
      providers: [
        TrackingIdService,
        {
          provide: CookieService,
          useClass: mockClass(CookieService)
        }
      ]
    });
    cookieService = TestBed.get(CookieService);
});

NestJS test:

let module: TestingModule;
let loggerService: ClassMock<LoggerService>;

beforeEach(async () => {
    module = await Test.createTestingModule({
      controllers: [],
      providers: [
        ConfigService,
        {
          provide: LoggerService,
          useClass: mockClass(LoggerService),
        },
      ],
    }).compile();

    loggerService = module.get(LoggerService);
});