how to write test cases for behaviorsubject in angular component code example

Example: how to write test cases form behaviorsubject

import { Injectable } from '@angular/core';import { HttpClient } from '@angular/common/http';@Injectable({  providedIn: 'root'})export class UserService {  public apiUrl = 'path/to/your/api';  constructor(private http: HttpClient) { }  // Http request with GET method  fetchUsers() {    return this.http.get<any>(this.apiUrl);  }}