在 Ionic 服务的单元测试中注入 <Platform> 时抛出的错误

我刚刚开始用 Ionic 3 开发我的第一个应用程序，我现在正在进行一些单元测试。现在我面临一个问题，“编译”一个Servicewhen的单元测试Platform是它的依赖项之一。

以下是摘要Service：

@Injectable()
export class MyService {
  constructor(public platform: Platform) {}

  myMethod(): Observable<any> {
    if (this.platform.is('android')) {
      return new Observable(android);
    else if (this.platform.is('ios')) {
      return new Observable(iOS);
    }
  }
}

这是我按照互联网上的一些教程制作的单元测试：

describe('XXX', () => {
  var service: MyService;

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

  it('should xxx', inject([MyService], (service) => {
    var result = service.mymethod();
    expect(result).toBeDefined();
  }));
});

我的测试配置是在这篇博客文章之后进行的。我还有一些其他spec文件可以成功运行，除了这个引发以下错误的文件：

PS C:\Workspaces\JS-TS\taccess> npm run test

> [email protected] test C:\Workspaces\JS-TS\taccess
> karma start ./test-config/karma.conf.js --single-run

(node:17164) DeprecationWarning: Tapable.plugin is deprecated. Use new API on `.hooks` instead
‼ ｢wdm｣:
i ｢wdm｣: Compiled with warnings.
i ｢wdm｣: Compiling...
‼ ｢wdm｣:
i ｢wdm｣: Compiled with warnings.
26 07 2018 07:20:43.963:INFO [karma]: Karma v2.0.5 server started at http://0.0.0.0:9876/
26 07 2018 07:20:44.003:INFO [launcher]: Launching browser Chrome with unlimited concurrency
26 07 2018 07:20:44.806:INFO [launcher]: Starting browser Chrome
26 07 2018 07:20:54.988:INFO [Chrome 68.0.3440 (Windows 10 0.0.0)]: Connected on socket u2KlYyff-qRa_fnHAAAA with id 6508927
Chrome 68.0.3440 (Windows 10 0.0.0) ERROR
  {
    "message": "An error was thrown in afterAll\nUncaught Error: Cannot find module './components/app/app-root'",
    "str": "An error was thrown in afterAll\nUncaught Error: Cannot find module './components/app/app-root'"
  }
Chrome 68.0.3440 (Windows 10 0.0.0) ERROR
  {
    "message": "An error was thrown in afterAll\nUncaught Error: Cannot find module './components/app/app-root'",
    "str": "An error was thrown in afterAll\nUncaught Error: Cannot find module './components/app/app-root'"
  }

Chrome 68.0.3440 (Windows 10 0.0.0): Executed 0 of 0 ERROR (0.008 secs / 0 secs)


Chrome 68.0.3440 (Windows 10 0.0.0): Executed 0 of 0 ERROR (0.142 secs / 0 secs)

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] test: `karma start ./test-config/karma.conf.js --single-run`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] test script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\xxx\AppData\Roaming\npm-cache\_logs\2018-07-26T05_20_56_762Z-debug.log

为什么我需要注入Platform服务？因为我使用的是BLE的 Cordova 插件，而且 iOS 和 Android 之间存在一些我需要管理的差异。

有没有人知道发生了什么？我究竟做错了什么？

注 1：我已经检查了删除依赖项，Platform并且测试（由于缺少 进行了一些修改Platform）工作得很好。