Angular 2 unit testing - @ViewChild is undefined

Question

I am writing an Angular 2 unit test. I have a @ViewChild subcomponent that I need to recognize after the component initializes. In this case it\'s a Timepicke

Answer 1

If you want to test the main component with a stub child component, you need to add a provider to the stub child component; as explained in the article Angular Unit Testing @ViewChild.

import { Component } from '@angular/core';
import { ChildComponent } from './child.component';

@Component({
  selector: 'app-child',
  template: '',
  providers: [
    {
      provide: ChildComponent,
      useClass: ChildStubComponent
    }
  ]
})
export class ChildStubComponent {
  updateTimeStamp() {}
}

Note the providers metadata, to use the class ChildStubComponent when ChildComponent is required.

You can then create your parent component normally, its child will be created with the type ChildStubComponent.