在Angular中，当我们使用HTTP拦截器时，我们无法使用路由器进行导航，因为路由器依赖于DOM，而HTTP拦截器在DOM之前执行。

但是，我们可以使用Angular的RouterTestingModule来模拟路由器，并在测试中使用它来进行导航。

以下是一个示例解决方法：

1. 创建一个MockRouter类，模拟路由器的navigate方法。

class MockRouter {
  navigate = jasmine.createSpy('navigate');
}

2. 在你的HTTP拦截器中注入Router，并使用RouterTestingModule进行导航。

import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent } from '@angular/common/http';
import { Router } from '@angular/router';

@Injectable()
export class MyInterceptor implements HttpInterceptor {
  constructor(private router: Router) {}

  intercept(request: HttpRequest, next: HttpHandler): Observable> {
    // 在需要导航的地方使用这个条件
    if (request.url.includes('navigate')) {
      const mockRouter = new MockRouter();
      mockRouter.navigate(['/example']);
    }

    return next.handle(request);
  }
}

3. 在测试中使用RouterTestingModule模拟路由器，并注入MyInterceptor。

import { TestBed, ComponentFixture, async } from '@angular/core/testing';
import { HttpClientTestingModule, HttpTestingController } from '@angular/common/http/testing';
import { RouterTestingModule } from '@angular/router/testing';

import { MyInterceptor } from './my-interceptor';

describe('MyInterceptor', () => {
  let interceptor: MyInterceptor;
  let httpMock: HttpTestingController;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [HttpClientTestingModule, RouterTestingModule],
      providers: [MyInterceptor]
    }).compileComponents();
  }));

  beforeEach(() => {
    interceptor = TestBed.inject(MyInterceptor);
    httpMock = TestBed.inject(HttpTestingController);
  });

  it('should navigate when URL includes "navigate"', () => {
    spyOn(interceptor['router'], 'navigate');

    const req = httpMock.expectOne('/api/navigate');
    req.flush({});

    expect(interceptor['router'].navigate).toHaveBeenCalledWith(['/example']);
  });
});

通过使用RouterTestingModule和模拟路由器，我们可以在HTTP拦截器中进行导航，并在测试中验证导航是否发生。