我是Angular2的新手,正在尝试在app.component.spec.ts
文件中编写测试。我的应用程序相对简单,除了它从第三方库(由同事编写)导入LoginComponent和LogoutComponent之外。这些组件现在分别用于路由登录或注销,非常简单。运行ng serve
编译正常,应用程序“顺利”运行。但是,运行ng test
会给我这个错误:
NullInjectorError: StaticInjectorError(DynamicTestModule)[LogoutComponent -> SessionService]:
StaticInjectorError(Platform: core)[LogoutComponent -> SessionService]:
NullInjectorError: No provider for SessionService!
LogoutComponent是从其他项目导入的。这个错误是否意味着我需要进入该项目并进行一些更改,还是应该在我的项目中以某种方式嘲笑SessionService?
规范代码:
import {} from 'jasmine';
import {async, TestBed} from '@angular/core/testing';
import {RouterTestingModule} from '@angular/router/testing';
import {AuthErrorStateService, LogoutComponent} from '@custom-library';
import {AppComponent} from './app.component';
import {AppErrorStateService} from './core/error-states/app-error-state.service';
import {TopNavComponent} from './core/top-nav/top-nav.component';
describe('AppComponent', () => {
beforeEach(async(() => {
TestBed
.configureTestingModule({
imports: [RouterTestingModule],
providers: [
AppErrorStateService, AuthErrorStateService
],
declarations: [AppComponent, TopNavComponent, LogoutComponent],
})
.compileComponents();
}));
it('should create the app', () => {
const fixture = TestBed.createComponent(AppComponent);
const app = fixture.debugElement.componentInstance;
expect(app).toBeTruthy();
});
it(`should have as title 'My App'`, () => {
const fixture = TestBed.createComponent(AppComponent);
const app = fixture.debugElement.componentInstance;
expect(app.title).toEqual('My App');
});
it('should render title in a h1 tag', () => {
const fixture = TestBed.createComponent(AppComponent);
fixture.detectChanges();
const compiled = fixture.debugElement.nativeElement;
expect(compiled.querySelector('h1').textContent).toEqual('Welcome to My App!');
});
});
答案 0 :(得分:1)
问题在于像这样声明TestBed
中的多个组件
declarations: [AppComponent, TopNavComponent, LogoutComponent]
导致测试调用compileComponents()
时实例化多个组件。发生这种情况时,declarations
数组中的每个组件都需要在providers
数组中声明其依赖项才能完成实例化。已声明的组件之一取决于SessionService
,但是提供程序中不存在该服务,因此您获得了NullInjectorError
。
有两种解决方法:
declarations
数组中声明一个组件并添加
schemas: [ CUSTOM_ELEMENTS_SCHEMA ]
到TestBed
配置
对象providers
数组