angular - 如何测试包含自定义表单控件的组件？

Question

我有这样一个组件

@Component({
      selector: 'app-custom-form-control',
      templateUrl: '<input>',
      providers: [
        {
          provide: NG_VALUE_ACCESSOR,
          useExisting: forwardRef(() => SelectComponent),
          multi: true
        }
      ]
    })
export class CustomFormControlComponent implements ControlValueAccessor {...}

如您所见，它是一个自定义表单控件。我在要测试的组件中使用它。

    @Component({
      selector: 'app-root',
      templateUrl: '<div [formGroup]="form">
          <app-custom-form-control formControlName="my_field"></app-custom-form-control>
      </div>',
    })
    export class AppComponent implements OnInit, OnDestroy {...}

那么我如何为我的测试模拟 app-custom-form-control？

当前的实现需要一个真正的组件...

  beforeEach(async(() => {
    const testRouter = new RouterStub();
    const testDataService = new DataServiceStub();
    TestBed.configureTestingModule({
      declarations: [
        AppComponent,
        CustomFormControlComponent // it is a real stuff
      ],
      imports: [
        ReactiveFormsModule
      ],
      providers: [
        { provide: Router, useValue: testRouter },
        { provide: DataService, useValue: testDataService }
      ],
      schemas: [ NO_ERRORS_SCHEMA ]
    }).compileComponents();
  }));

否则(没有声明组件)我得到一个错误失败:没有名称的表单控件的值访问器:app-custom-form-control

Answer 1

在对 Angular 应用程序进行测试时，您可以遵循两种主要方法(和混合):

1- Stubbing unneeded components , 其中

(...) you create and declare stub versions of the components anddirective that play little or no role in the tests (...)

2-NO_ERRORS_SCHEMA哪个

(...) tells the Angular compiler to ignore unrecognized elements and attributes (...)

对于最后一个，编译器在 AppComponent 模板中遇到 app-custom-form-control 选择器时不会抛出错误。

3- Use both techniques together

选择一种或另一种方法完全取决于您，因为这取决于您要通过测试达到的最终目标。

---

应用方法 1 会是这样的:

describe('AppComponent', () => {

// component stub
@Component({selector: 'app-custom-form-control', template: ''})
class CustomFormControlComponentStub {}
//...
  beforeEach(async(() => {
    const testRouter = new RouterStub();
    const testDataService = new DataServiceStub();
    TestBed.configureTestingModule({
      declarations: [
        AppComponent,
        CustomFormControlComponentStub // it is fake! stuff
      ],
      // ... code omitted
    }).compileComponents();
  }));
//...
});