javascript - 如何监视原生 JavaScript 函数？比如.find()？

Question

我正在尝试在以下内容中模拟 this.editedComponentDetailsData.find :

editButtonClicked(event) {
    let rowData = this.editedComponentDetailsData.find((row) => {
      return row.operationalSequenceNumber == this.rowKey;
    })
  }

这不起作用:

 it('should do something', () => {
    let result=spyOn(subject.editedComponentDetailsData.prototype,'find').and.returnValue({prop1:''});
  });

Answer 1

只需为 editedComponentDetailsData 分配一个像空数组一样可迭代的属性，然后您就可以监视查找，但您只需在没有原型(prototype)的情况下访问它，就像在组件内部一样。

beforeEach(() => {
    TestBed.resetTestEnvironment();
    TestBed.initTestEnvironment(BrowserDynamicTestingModule,
      platformBrowserDynamicTesting())

    TestBed.configureTestingModule({
      declarations: [AppComponent],
      providers: [
        AppComponent
      ],

      schemas: [NO_ERRORS_SCHEMA]
    });
    fixture = TestBed.createComponent(AppComponent);
    subject = fixture.componentInstance;
    subject.editedComponentDetailsData=[]; //mock with empty array
  });
  it('should do something', () => {
    let result=spyOn(subject.editedComponentDetailsData,'find').and.returnValue({prop1:''}); //the spy
  });