Failed: Template parse errors: 'app-header' is not a known element

Question

homepage.module.ts

import { NgModule, CUSTOM_ELEMENTS_SCHEMA } from "@angular/core";
import { CommonModule } from "@angular/common";
import { HomepageComponent } from "./homepage.component";
import { SharedModule } from "../shared/shared.module";


@NgModule({
  declarations: [HomepageComponent],
  imports: [
    CommonModule,
    SharedModule
  ],
  exports: [HomepageComponent],
  providers: [],
  schemas: [CUSTOM_ELEMENTS_SCHEMA]
})
export class HomepageModule {}


shared-module.ts

import { NgModule, CUSTOM_ELEMENTS_SCHEMA } from "@angular/core";
import { CommonModule } from "@angular/common";
import { HeaderComponent } from "./header/header.component";
@NgModule({
  declarations: [
    HeaderComponent,
  ],
  imports: [
    CommonModule,
  ],
  exports: [
    HeaderComponent,
  ],
  schemas: [CUSTOM_ELEMENTS_SCHEMA]
})
export class SharedModule {}


homepage.component.html

<app-header (toggleSideBarForMe)="sideBarToggler($event)"></app-header>


app.module.ts

import { HomepageModule } from "./homepage/homepage.module";
@NgModule({
  declarations: [AppComponent],
  imports: [
    HomepageModule,
    ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule {}

while running karma , i am getting the errors . : Failed: Template parse errors: 'app-header' is not a known element: 1. If 'app-header' is an Angular component, then verify that it is part of this module. 2. If 'app-header' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. ("[ERROR ->]

Do i need to add anything in the homepage.component.spec file ?

Yes, you need to meke sure the testing module contains everything needed, just as a normal module. — JB Nizet

Vincent TOSSOU Vincent TOSSOU · Accepted Answer · 2020-06-23T07:12:59

Try to see if your component who must use "app-header" and HeaderComponent also are imported in your module
Try to see if one of your components is not imported in 2 or more modules

Failed: Template parse errors: 'app-header' is not a known element

1 Answers