如何对此canActivate保护进行单元测试

import { Injectable } from '@angular/core';
import { CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot, UrlTree, Router } from '@angular/router';
import { Observable } from 'rxjs';
import { AuthService } from './auth.service';

@Injectable({
  providedIn: 'root'
})
export class AuthGuard implements CanActivate {
  constructor(private authService: AuthService, private router: Router) {}

  canActivate(
    route: ActivatedRouteSnapshot,
    state: RouterStateSnapshot): Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree {
    const isAuthenticated = this.authService.isAuthenticated();
    if (isAuthenticated) {
      return true;
    } else {
      this.router.navigate(['/login']);
      return false;
    }
  }
}

import { TestBed } from '@angular/core/testing';
import { RouterTestingModule } from '@angular/router/testing';
import { AuthGuard } from './auth.guard';
import { AuthService } from './auth.service';

describe('AuthGuard', () => {
  let guard: AuthGuard;
  let authServiceMock: any;

  beforeEach(() => {
    authServiceMock = {
      isAuthenticated: jasmine.createSpy('isAuthenticated').and.returnValue(true)
    };

    TestBed.configureTestingModule({
      imports: [RouterTestingModule],
      providers: [
        AuthGuard,
        { provide: AuthService, useValue: authServiceMock }
      ]
    });

    guard = TestBed.inject(AuthGuard);
  });

  it('should allow access if user is authenticated', () => {
    expect(guard.canActivate(null, null)).toBeTrue();
    expect(authServiceMock.isAuthenticated).toHaveBeenCalled();
  });

### 遇到的问题及解决方法

**问题**：在测试中，`AuthGuard` 的 `canActivate` 方法没有按预期工作。

**原因**：
1. 依赖项（如 `AuthService`）没有正确模拟。
2. `Router` 的导航方法没有被正确触发或验证。

**解决方法**：
1. 确保使用 `jasmine.createSpy` 或其他模拟库正确模拟了所有依赖项。
2. 使用 `RouterTestingModule` 和 `Router` 的 `navigate` 方法的 spy 来验证导航行为。

```typescript
import { Router } from '@angular/router';

// 在 beforeEach 中
const routerMock = {
  navigate: jasmine.createSpy('navigate')
};

TestBed.configureTestingModule({
  // ...
  providers: [
    AuthGuard,
    { provide: AuthService, useValue: authServiceMock },
    { provide: Router, useValue: routerMock }
  ]
});

// 在测试中
it('should redirect to login if user is not authenticated', () => {
  authServiceMock.isAuthenticated.and.returnValue(false);
  expect(guard.canActivate(null, null)).toBeFalse();
  expect(routerMock.navigate).toHaveBeenCalledWith(['/login']);
});