Angular 4 管道单元测试不适用于基本管道

Question

Karma error I get: TypeError: Cannot read property '0' of undefined

这是我的烟斗（非常基础）：

import { Pipe, PipeTransform } from "@angular/core";

@Pipe({
  name: "userPipe",
  pure: true
})

export class MyFilter implements PipeTransform {
   transform(items: any, [listOfItems]: any) {

     // Example of a pipe: listOfItems = listOfItems.filter(item => item.type === "test");

     return listOfItems;
  }
}

这是我的管道单元测试：

import { MyFilter } from "./user.pipe";

describe("userPipe", () => {
  let pipe: MyFilter;
  let fakeResponse = ["abc"];

  beforeEach(() => {
    pipe = new MyFilter();
  });

  it("transforms abc to abc", () => {
    expect(pipe.transform(fakeResponse)).toEqual(fakeResponse);
  });
});

Answer 1

首先更新您的转换函数，测试将使用此代码

export class MyFilter implements PipeTransform {
   transform( items: Array<any> ) {
     return listOfItems;
  }
}

Angular 4 管道单元测试不适用于基本管道

Angular 4 pipe unit test not working for basic pipe

unit-testing

jasmine

karma-jasmine

angular2-pipe

angular