单元测试 - Angular 9 中未定义的 ag-grid API onFilterChanged

Question

我正在 Angular 中编写 Ag-grid 的单元测试用例，其中有 Angular Grid：外部过滤器，它是切换过滤器复选框。我收到“TypeError：无法读取未定义的属性‘onFilterChanged’”

我正在测试这个方法：

toggleCheckboxMethod({ checked }): void {
    isChecked = checked;
    this.gridApi.onFilterChanged(); //when this method initiates it causes for test to fail
  }

 beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [
        RouterTestingModule.withRoutes([]),
        HttpClientModule,
        HttpClientTestingModule,
        AgGridModule.withComponents([]),
        MatDialogModule,
        BrowserAnimationsModule
      ],
      declarations: [ TestComponent ],
      providers: []

    })
    .compileComponents();
  }));

beforeEach(() => {
    fixture = TestBed.createComponent(TestComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
});

  it('should toggle checkbox', () => {
    let isChecked = false;
    spyOn(component, 'toggleCheckboxMethod').and.callThrough();
    component.toggleCheckboxMethod({ checked: true });
    expect(component.toggleCheckboxMethod).toHaveBeenCalled();
    expect(isChecked).toEqual(true);
  });

Answer 1

我认为gridApi在你断言的那一刻是未定义的。测试ag-grid可能很奇怪，您必须等待其异步任务完成才能断言。

我会做这样的事情：

创建一个像这样的实用函数，您可以在继续之前等待某些事情成立：

import { interval } from 'rxjs';
.....
export const waitUntil = async (untilTruthy: Function): Promise<boolean> => {
  while (!untilTruthy()) {
    await interval(25).pipe(take(1)).toPromise();
  }
  return Promise.resolve(true);
};

it('should toggle checkbox', async (done: DoneFn) => {
    let isChecked = false;
    spyOn(component, 'toggleCheckboxMethod').and.callThrough();
    // wait until component.gridApi is truthy before carrying forward
    await waitUntil(() => !!component.gridApi);
    component.toggleCheckboxMethod({ checked: true });
    expect(component.toggleCheckboxMethod).toHaveBeenCalled();
    expect(isChecked).toEqual(true);
    done(); // call done to let Jasmine know you're done (this could be optional)
  });

这是另一个与您有相同问题的人，如果您不喜欢我的解决方案，您可能需要检查答案的解决方案。