角度单元测试：如何对.map（）进行单元测试？

Question

我需要测试一种服务方法，但不确定如何通过调用某些注入的服务方法来运行部分代码，以实现100％的代码覆盖率。

要测试的服务方法：

@Injectable()
export class BomRevisiosnsService {
  constructor(
    private baseService: BaseService,
    private appConstants: AppConstants,
    private dmConstants: DMConstants
  ) { }

  public getRevisionsData(): any {
    var itemId = this.appConstants.userPreferences.modelData['basicDetails']['itemId'];
    let url = this.dmConstants.URLs.GETBOMREVISIONS + itemId + "/GetRevisionsAsync";
    let headers = {
      "Content-Type": "application/json",
      UserExecutionContext: JSON.stringify(this.appConstants.userPreferences.UserBasicDetails),
    }
    if (itemId != null || itemId != undefined) {
      return this.baseService.getData(url, headers)
        .map(response => {
          // this area not getting covered.
          return response;
        });
    }
  }
}

我如何覆盖：

.map(response => {
  return response;
});

在下面的：

测试：

it('should return response if itemId is not null or undefined', () => {
  let mockData = [1,2,3];
  let mockObservable = Observable.of(mockData);
  spyOn(baseService, 'getData').and.returnValue(mockObservable);
  appConstants.userPreferences.modelData['basicDetails']['itemId']=4; // itemId not null or undefined
  dMConstants.URLs.GETBOMREVISIONS ="dummy url";
  subject.getRevisionsData();
  expect(baseService.getData).toBe(mockData); // How do I test .map()?
});

Answer 1

it('should return response if itemId is not null or undefined', () => {
  ...
  const spy = spyOn(baseService.getData).and.return(mockedData)// you need to define data returned by baseService.getData
  const result = subject.getRevisionsData();
  expect(spy).toHaveBeenCalled(); // How do I test .map()?
  expect(result).toEqual(mockedData);// for simple map it will be the same thing that is returned for more complicated map it may differ
});