如何对使用@Self装饰ngControl的反应组件进行单元测试 [英] How to unit test a reactive component where ngControl is decorated with @Self

问题描述

我已经通过注入NgControl编写了一个反应组件，并使用@Self装饰器对其进行了装饰.我的问题与此类组件的单元测试有关. 请查看下面的代码:

I've written a reactive component by injecting the NgControl and which is decorated using the @Self decorator. My problem is related to unit testing of such component. Please look at the code below:

免责声明:我已经快速复制了代码并进行了一些内联更改.因此，这可能不是编译器满意的代码.

Disclaimer: I've quickly copied the code and made some inline changes. So, this might not be a compiler happy code.

我的反应组件:

@Component({
  selector: 'text-input',
  templateUrl: '<input type="text" class="native_input" />'
})
class TextInput implements ControlValueAccessor {
  protected constructor(@Self() public controlDir: NgControl) {

    this.controlDir.valueAccessor = this;
  }

  // ...followed by other ControlValueAccessor methods

}

单元测试:

describe('TextInput -', () => {

   let fixture: ComponentFixture<TextInputHost>;
   let textInput: TextInput;

   let inputElement: HTMLInputElement;

   beforeEach(async(() => {
     TestBed.configureTestingModule({
       declarations: [
         TextInput, TextInputHost
       ],
       imports: [
         FormsModule, ReactiveFormsModule
       ]
     });
  }));

  beforeEach(fakeAsync(() => {
    fixture = getTestBed().createComponent(TextInputHost);
    textInput = fixture.componentInstance.textInputComponent;
    textInput.writeValue('TestValue');
    inputElement = fixture.debugElement
       .query(By.css('native_input')).nativeElement;
    fixture.detectChanges();
    tick();
  }));

  it('Should have the initial value applied.', () => {
    expect(inputElement.value).toBe('TestValue');
  });

});

// Host component
@Component({
  template: `
   <form [formGroup]="pageForm">
    <text-input formControlName="testInput">
    </text-input>
   </form>`
})
class TextInputHost {
   @ViewChild(TextInput)
   public textInputComponent: TextInput;

   public pageForm: FormGroup = new FormGroup({
     testInput: new FormControl('Initial Value')
   });
}

每当我尝试运行上述单元测试时.它失败，并显示以下错误: Template parse errors: No provider for NgControl --> <text-input>....</text-input>

Whenever I try to run the above unit test. It fails with the following error: Template parse errors: No provider for NgControl --> <text-input>....</text-input>

因此，我正在寻找一种成功运行上述单元测试的方法.我正在寻找的是一种将NgControl注入到TextInput组件的方法.

So I'm looking for a way to successfully run the above unit test. What, I'm looking for is a way to inject the NgControl to the TextInput component.

推荐答案

如果有人偶然发现了这个问题，我将使用TestBed类的overrideComponent()方法解决该问题.

If anybody stumbles upon this question, I solved it using the overrideComponent() method of the TestBed class.

注意:如果您认为自己还有其他答案，请随时回答.

要注入NgControl:

To inject the NgControl:

beforeEach(async(() => {
     TestBed.configureTestingModule({
       declarations: [
         TextInput, TextInputHost
       ],
       imports: [
         FormsModule, ReactiveFormsModule
       ]
    })
    .overrideComponent(TextInput, {
        set: {
          providers: [
            {
              provide: NgControl,
              useValue: new FormControlDirective([], [], null, null)
            }
         ]
       }
    });
 }));

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