@Injectable()
export class HnService {
  constructor(private http: HttpClient) {}

  getTopPosts(endpoint) {
    return this.http.get(endpoint);
  }
}

@Injectable()
export class HnResolver implements Resolve<any> {
  constructor(private hnService: HnService) {}

  resolve() {
    return this.hnService.getTopPosts(?);
  }
}