Angular执行测试报错: ‘app-messages’ is not a known element
本机环境:
$ ng --version
Angular CLI: 7.1.1
Node: 10.11.0
OS: darwin x64
Angular: 7.1.1
错误详情:
Chrome 72.0.3622 (Mac OS X 10.13.6) AppComponent should create the app FAILED
'app-messages' is not a known element:
1. If 'app-messages' is an Angular component, then verify that it is part of this module.
2. If 'app-messages' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. ("
<router-outlet></router-outlet>
[ERROR ->]<app-messages></app-messages>"): ng:/
问题分析:
使用 ng serve
运行应用,通过访问 http://localhost:4200
,都运行正常,未见报错。但是,执行 ng test
就提示一大推错误,这是为什么呢?
提示这个“不是已知元素”,一般是没有引入组件,可是在代码里已经都引入过了,为何还会这样报错呢?
最后发现,在应用代码里需要引入外,在测试代码(*.spec.ts
)里也要再次引入相应的组件或模块。
比如上边例子中,在AppComponent
组件中,使用了 app-messages
组件模板,但是并没有引入 app-messages 组件(MessagesComponent)。
解决办法:
引入相应的组件。
类似XXX is not a known element
的错误还有很多,引入相应的组件即可。
比如,在 DashboardComponent 组件中,使用了 app-hero-search
组件模板,却没有引入 HeroSearchComponent
组件:
Chrome 72.0.3622 (Mac OS X 10.13.6) DashboardComponent should create FAILED
'app-hero-search' is not a known element:
1. If 'app-hero-search' is an Angular component, then verify that it is part of this module.
2. If 'app-hero-search' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. ("
</div>
[ERROR ->]<app-hero-search></app-hero-search>
"): ng:/
修复后代码:
修改后 dashboard.component.spec.ts
的 beforeEach
部分代码如下:
beforeEach(async(() => {
TestBed.configureTestingModule({
declarations: [
DashboardComponent,
MessagesComponent,
HeroSearchComponent
],
imports:[
RouterTestingModule,
HttpClientTestingModule
]
})
.compileComponents();
}));
更多内容,请查看项目代码:
https://github.com/cnwyt/angular-tour-of-heroes
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