Angular MockClientService没有提供程序

我创造了假服务：

@Injectable()
class MockClientService {
 CHAT_URL = '';
 public planOrders = new Subject<PlanOrderModel[]>();
 private subject: Rx.Subject<MessageEvent>;

constructor() {
this.planOrders.next([{
  PlanDirective: 'Create Directive', Physician: 'REMOTE-RO', PlanPriority: 2,
  PlanNotes: '', PlanOrderId: 'Order_1', PatientDetails: { 'ID': '210598', 'Name': 'Ruffin Abdullah', 'AnonymizedID': '' },
  StructureSetID: 'CT_1', MachineID: 'Scanner Test', LastUpdated: '05/12/2018', DueDate: '05/12/2018', Status: '2',
  GatewayID: 0, selected: false, active: true
}]);

即使在注入MockClientService并获得错误后：

---

NullInjectorError:MockClientService没有提供程序

如评论中所述，无需调用

覆盖组件

，您只需在

提供程序

数组中提供模拟服务，如下所示：

beforeEach(async(() => {
  TestBed.configureTestingModule({
    declarations: [ DummyComponent ],
    providers: [{
      provide: ClientService,
      useClass: MockClientService
    }]
  }).compileComponents();
}));

我做了一个小的stackblitz，展示了如何在一个单元中模拟服务 测试

---

您不需要执行“overrideComponent”。只要使用{provide:ClientService，useClass:mockClientService}将您的mockClientService包含到提供者中，它就应该可以工作了。我也试过了。它给出了相同的错误，然后又给出了alsoRemove@Injectable（）

beforeEach(async(() => {
  TestBed.configureTestingModule({
    declarations: [ DummyComponent ],
    providers: [{
      provide: ClientService,
      useClass: MockClientService
    }]
  }).compileComponents();
}));