测试管道对服务的依赖 [英] Test pipe with dependencies on services

问题描述

我有一个管道，可以对HTML进行如下处理：

I have a pipe that sanatises HTML as below:

import { Pipe, PipeTransform } from '@angular/core';
import { DomSanitizer } from '@angular/platform-browser';

@Pipe({
    name: 'sanitiseHtml'
})

export class SanitiseHtmlPipe implements PipeTransform {

constructor(private _sanitizer: DomSanitizer) {}

    transform(value: any): any {
      return this._sanitizer.bypassSecurityTrustHtml(value);
    }

}

我要按以下方式对其进行测试：

I want to test it as below:

describe('Pipe: Sanatiser', () => {
    let pipe: SanitiseHtmlPipe;

    beforeEach(() => {
        pipe = new SanitiseHtmlPipe(new DomSanitizer());
    });

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

DomSanatizer是一个抽象类，通过将其传递给构造函数由typescript自动装配：

The DomSanatizer is an abstract class which is autowired by typescript by passing it into a constructor:

constructor(private _sanitizer: DomSanitizer) {}

当前我得到打字稿错误：

Currently I get the typescript errror:

无法创建抽象类'DomSanitizer'的实例。

Cannot create an instance of the abstract class 'DomSanitizer'.

有人实例化在Angular中传递给构造函数的依赖项时，有人知道吗？还是测试这种东西的方法是什么？

Does anyone know what typescript does when instantiating dependencies passed into a constructor in Angular? Or what the way to test something like this is?

推荐答案

由于管道中的DI，您需要配置测试环境（测试台）以解决依赖关系：

Because of the DI in your pipe, you need to configure a test environment (test bed) to resolve the dependency:

import { BrowserModule, DomSanitizer } from '@angular/platform-browser';
import { inject, TestBed } from '@angular/core/testing';

describe('SanitiseHtmlPipe', () => {
  beforeEach(() => {
    TestBed
      .configureTestingModule({
        imports: [
          BrowserModule
        ]
      });
  });

  it('create an instance', inject([DomSanitizer], (domSanitizer: DomSanitizer) => {
    let pipe = new SanitiseHtmlPipe(domSanitizer);
    expect(pipe).toBeTruthy();
  })); 
});

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