import {of as observableOf, Observable } from 'rxjs'; // declare a stub service export class HostWindowServiceStub { private width: number; constructor(width) { this.setWidth(width); } setWidth(width) { this.width = width; } isXs(): Observable<boolean> { return observableOf(this.width < 576); } isXsOrSm(): Observable<boolean> { return this.isXs(); } }