应用测试返回"NullInjectorError: No provider for Location!"

Question

使用 Karma 在 Angular 7 中测试应用程序，我无法删除 subj 中的错误。

我已经搜索了各个地方(主要是在这里(，但解决方案要么不起作用，要么与我的情况无关。

App.component.html：

<app-header></app-header>
<router-outlet></router-outlet>

Header.component.ts：

import { Component, OnInit, ViewChild, ElementRef, AfterViewInit, EventEmitter, Output } from '@angular/core';
import { Router } from '@angular/router';
import { Location } from '@angular/common';
@Component({
    selector: 'app-header',
    templateUrl: './header.component.html',
    styleUrls: ['./header.component.less']
})
export class HeaderComponent implements AfterViewInit, OnInit {
    constructor(private location: Location, private router: Router) { 
        setInterval(() => {
            this.now = new Date();
        }, 1000);
    }
...
    onKeyDown(event: KeyboardEvent): void {
        event.preventDefault();
        if (event.which === this.KEY_ESCAPE){
            if (this.router.url !== '/'){
                this.location.back();
            }
        }
    }

App.component.spec.ts：

import { TestBed, async } from '@angular/core/testing';
import { AppComponent } from './app.component';
import { HeaderComponent } from './header/header.component';
import { RouterOutlet } from '@angular/router';
describe('AppComponent', () => {
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [
        AppComponent,
        HeaderComponent,
        RouterOutlet
      ],
    }).compileComponents();
  }));
  it('should create the app', () => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;
    expect(app).toBeTruthy();
  });

AppComponent should create the app
Error: StaticInjectorError(DynamicTestModule)[HeaderComponent -> Location]: 
  StaticInjectorError(Platform: core)[HeaderComponent -> Location]: 
    NullInjectorError: No provider for Location!

Answer 1

就我而言，我已经在使用路由器测试模块，它不应该引发此错误。我从错误的位置导入了位置，因此出现了错误。"位置"应从此处导入：

import {Location} from '@angular/common';

在导入中，您应该只像这样导入路由器测试模块：

TestBed.configureTestingModule({
      imports: [
        RouterTestingModule.withRoutes(
          [
            {path: 'add', component: DummyComponent, pathMatch: 'full'}
          ]
        )
      ],

然后你可以像这样使用位置：

it('Should navigate to / before + button click', () => {
    const location: Location = TestBed.get(Location);
    expect(location.path()).toBe('');
  });

只是不要忘记从@angular/公共导入位置

Answer 2

修复了它：我需要做的就是导入RouterModule.forRoot([])，这似乎是一个常见的错误，因为它修复了很多StaticInjectorError(DynamicTestModule)错误。

Answer 3

测试期间NullInjectorError: No provider for Location!的替代方法是导入RouterTestingModule。

前任。 mycomponent.spec.ts:

    import { RouterTestingModule } from '@angular/router/testing';
    ...
    beforeEach(() => TestBed.configureTestingModule({
            imports: [ RouterTestingModule ]
    }));

Answer 4

你能试着import> CommonModule

吗

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [CommonModule]
      declarations: [
        AppComponent,
        HeaderComponent,
        RouterOutlet
      ],
    }).compileComponents();
  }));