问题

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在一个新的Angular 15 CLI应用中的最小工作示例：

* 一个（空白）服务 `HelperService`
* 这个服务通过新的 `inject()` 调用注入到 `DemoPipe` 中：
```typescript
export class DemoPipe implements PipeTransform {
  private readonly helper = inject(HelperService);
  ...
}

由NG-cli创建的默认管道测试将失败，因为构造函数调用发生在DI上下文之外：

it('创建一个实例', () => {
  const pipe = new DemoPipe();
  expect(pipe).toBeTruthy();
});

错误：NG0203：inject() 必须从注入上下文中调用，如构造函数、工厂函数、字段初始化程序或与 `EnvironmentInjector#runInContext` 一起使用的函数。详细信息请参阅 https://angular.io/errors/NG0203
        错误属性：Object({ code: -203 })

是否有任何Karma包装器可以提供缺失的环境？

<details>
<summary>英文:</summary>

A minimum working example, in a fresh Angular 15 CLI app:

* A (blank) service `HelperService`
* This service gets injected into `DemoPipe` with the new `inject()` call:
```typescript
export class DemoPipe implements PipeTransform {
  private readonly helper = inject(HelperService);
  ...
}

The default pipe test created by NG-cli will fail, as the constructor call happens outside the DI context:

it('create an instance', () => {
  const pipe = new DemoPipe();
  expect(pipe).toBeTruthy();
});

Error: NG0203: inject() must be called from an injection context such as a constructor, a factory function, a field initializer, or a function used with `EnvironmentInjector#runInContext`. Find more at https://angular.io/errors/NG0203
        error properties: Object({ code: -203 })

Is there any wrapper I could use in Karma to provide the missing environment?

答案1

得分: 3

你可以尝试以下代码：

describe('DemoPipe', () => {
 let pipe: DemoPipe;

  beforeEach(async () => {
    TestBed.configureTestingModule({ providers: [DemoPipe, HelperService] });
  });

  it('create an instance', () => {
    pipe = TestBed.inject(DemoPipe);
    expect(pipe).toBeTruthy();
  });
}

我尝试过，它可以正常工作。

describe('DemoPipe', () => {
 let pipe:DemoPipe;

  beforeEach(async () => {
    TestBed.configureTestingModule({ providers: [DemoPipe,HelperService] });
  });

it('create an instance', () => {
  pipe = TestBed.inject(DemoPipe);
  expect(pipe).toBeTruthy();
});