角4管單元測試不是基本的管道工作

Question

角4管單元測試不工作的基本管

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

這是我管（很基本的）：

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; 
    } 
} 

這是我的管道單元測試：

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

首先更新你的變換函數，測試將使用這個代碼

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