Karma + Jasmine:无法读取属性'getComponentFromError'

Question

我正在学习本教程:https://angular.io/guide/testing#component-test-scenarios for karma + jasmine unit testing.这是我的代码:

import { AppComponent } from "./app.component";
import { ComponentFixture, TestBed } from "@angular/core/testing";

describe('AppComponent', () => {

let component: AppComponent;
let fixture:   ComponentFixture<AppComponent>;
let h1:        HTMLElement;

beforeEach(() => {
  TestBed.configureTestingModule({
    declarations: [ AppComponent ],
  });
  fixture = TestBed.createComponent(AppComponent);
  component = fixture.componentInstance; 
  h1 = fixture.nativeElement.querySelector('h1');
});

it('should display original title', () => {
    expect(h1.textContent).toContain("Ciao");
  });

});

当我运行测试时,我得到以下异常:

 TypeError: Cannot read property 'getComponentFromError' of null
    at TestBed._initIfNeeded (D:/Users/apwzp/AppData/Local/Temp/karma-typescript-bundle-11944DDd01l2f5Y0P.js:1020:52)
    at TestBed.createComponent (D:/Users/apwzp/AppData/Local/Temp/karma-typescript-bundle-11944DDd01l2f5Y0P.js:1174:14)
    at Function.TestBed.createComponent (D:/Users/apwzp/AppData/Local/Temp/karma-typescript-bundle-11944DDd01l2f5Y0P.js:876:29)
    at UserContext.<anonymous> (assets/app/app.component.spec.ts:14:20 <- assets/app/app.component.spec.js:13:37)
    at ZoneDelegate.invoke (node_modules/zone.js/dist/zone.js:388:26)
    at ProxyZoneSpec.onInvoke (node_modules/zone.js/dist/proxy.js:79:39)
    at ZoneDelegate.invoke (node_modules/zone.js/dist/zone.js:387:32)
    at Zone.run (node_modules/zone.js/dist/zone.js:138:43)
    at UserContext.<anonymous> (node_modules/zone.js/dist/jasmine-patch.js:106:34)

有谁知道如何解决它？

Answer 1

我碰到了类似的东西,在这里找到答案:无法读取null jasmine angular 2的属性'injector'.

我刚刚将这个添加到我的beforeEach()方法中,它为我解决了这个错误(还有一些其他我必须克服才能完全完成所有工作).

 TestBed.resetTestEnvironment();
 TestBed.initTestEnvironment(BrowserDynamicTestingModule,
    platformBrowserDynamicTesting());

基本上只是改变了这个问题:

beforeEach(() => {
  TestBed.configureTestingModule({
    declarations: [ AppComponent ],
   });
  fixture = TestBed.createComponent(AppComponent);
  component = fixture.componentInstance; 
  h1 = fixture.nativeElement.querySelector('h1');
});

至

import { BrowserDynamicTestingModule,
platformBrowserDynamicTesting } from '@angular/platform-browser-dynamic/testing';

beforeEach(() => {
 TestBed.resetTestEnvironment();
 TestBed.initTestEnvironment(BrowserDynamicTestingModule,
    platformBrowserDynamicTesting());

  TestBed.configureTestingModule({
    declarations: [ AppComponent ],
   });
  fixture = TestBed.createComponent(AppComponent);
  component = fixture.componentInstance; 
  h1 = fixture.nativeElement.querySelector('h1');
});