How to correctly test a class in angular?

Question

Angular

The question may not be the most important, and many rather pass by, because if it works in the browser window, then it’s okay, but I want to get to the bottom of the truth. In short, there are three components in angular - all are registered, everything works, but ng test swears at the creation of the last component, where the class looks like:

import {Item} from "../item";

@Component({
  selector: 'app-item',
  templateUrl: './item.component.html',
  styleUrls: ['./item.component.sass']
})
export class ItemComponent implements OnInit {

  @Input('item') data : Item;
  @Input('fir') fname : string;

*лишнее убрал
}

And the creation of a component occurs in another component through:

<app-item
     *ngFor="let i of items"
     [item]="i"
     [fir]="fir">
</app-item>

As far as I understand, this component itself does not create anything, because accessing it from the top component in the constructor:

this.items = [
      new Item(" _f1", " _s1"),
      new Item(" _f2", " _s2"),
    ];

or can it somehow artificially write data in the spec file to create a component, or is it not necessary, given that the upper component passes the check with all its initialization?