Angular单元测试错误：可以解析ExtConfig的所有参数：（？，？）

Question

我是角度单位测试的新手。运行ng Test命令时，该单元测试失败了：

Can't resolve all parameters for ExtConfig: (?, ?)

如何解决此错误？

downloadscomponent.ts

import { Component, OnInit, ViewChild } from '@angular/core';
import { ExtConfig} from 'donwalods-portl';
import { Language } from '../../../language';

@Component({
    selector: 'lib-downloads',
    templateUrl: './downloads.component.html',
    styleUrls: ['./downloads.component.scss']
})

export class DownloadsComponent implements OnInit {

    constructor(
        private readonly configuration: ExtConfig;
    ) {
        this.lang = configuration.instance.languageMap as any as Language;
    }
  // more code
}

donwloadcomponent.spec.ts

import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { ExtConfig} from 'donwalods-portl'
import { DownloadsComponent } from './downloads.component';

describe('DownloadsComponent', () => {

    let fixture: ComponentFixture<DownloadsComponent>;

    beforeEach(async(() => {
        TestBed.configureTestingModule({
            declarations: [
                DownloadsComponent
            ],
            providers: [{ provide: ExtConfig}]
        }).compileComponents();
    }));

    it('should create the component', () => {
        fixture = TestBed.createComponent(DownloadsComponent);
        const app = fixture.debugElement.componentInstance;
        expect(app).toBeTruthy();
    });
});

Answer 1

看起来您的ExtConfig提供商具有一些依赖项，这些依赖项在testbed模块中未声明。

您将必须包括那些缺失的依赖项或模拟ExtConfig服务。

模拟提供商的一个示例可能是以下内容（请记住在方法中返回有效的内容）：

export class ExtConfigMock {
    private readonly _context;
    private readonly _instance;
    constructor() {
        // Mock constructor
    }

    instance() {
        // Mocked method, return something
    };
    context() {
        // Mocked method, return something
    };
}

然后，在配置testbed模块时，请使用此模拟代替原始提供商：

beforeEach(async(() => {
        TestBed.configureTestingModule({
            declarations: [
                DownloadsComponent
            ],
            providers: [
              { provide: ExtConfig, useClass: ExtConfigMock }
            ]
        }).compileComponents();
    }));