如何在Angular 5服务的构造函数中侦测/模拟方法调用？

import { Injectable } from '@angular/core';

@Injectable()
export class MyService {
  constructor(private dependencyService: DependencyService) {
    // 在构造函数中侦测/模拟方法调用
    this.dependencyService.someMethod();
  }
}

import { TestBed } from '@angular/core/testing';

describe('MyService', () => {
  let myService: MyService;
  let dependencyService: DependencyService;

  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [MyService, DependencyService]
    });

    myService = TestBed.inject(MyService);
    dependencyService = TestBed.inject(DependencyService);
  });

  it('should detect/mock method call in constructor', () => {
    spyOn(dependencyService, 'someMethod');
    myService = new MyService(dependencyService);
    expect(dependencyService.someMethod).toHaveBeenCalled();
  });
});