从单元测试 Angular 5 & Karma/Jasmine 访问 `declare`d 变量

Question

我正在尝试对一个组件进行单元测试，该组件具有使用declare关键字声明的变量，并且它有几个方法，然后在组件中稍后调用，如下所示：

import {
  Component,
  OnInit
} from '@angular/core';
import {
  AlertController,
  App,
  Events,
  Platform
} from "ionic-angular";

declare
let PushNotification: any;

@Component({
  selector: 'push',
  template: ``
})
export class PushComponent implements OnInit {

  nav: any;
  _push: any;

  constructor() {}

  ngOnInit() {

    // ...

    this._push = PushNotification.init({
      android: {
        senderID: '...'
      },
      ios: {
        alert: "true",
        badge: false,
        sound: 'false'
      },
      windows: {}
    });

    /**
     * On Registration, we want to register the device with BE
     */
    this._push.on('registration', (data) => {

      // ...

    });

    /**
     * If we have a notification come through we need to work out what we are doing with it
     */
    this._push.on('notification', (notification) => {

      // ...

    });
  }

  /**
   * Based on the payload we need to perform different actions
   * @param payload
   */
  public pushAction(payload: any) {
    // ...
  }

  /**
   * The user has received a notification while using the app so we need to show an alert
   * @param notification
   */
  public pushAlert(notification: any) {
    // ...
  }

  /**
   * Reset the badge number to 0
   */
  public resetBadge() {
    // ...
  }

  /**
   * Register deviceId and platform
   * @param registrationId
   */
  public registerPush(registrationId) {
    // ...
  }

  /**
   * De-Register the deviceId
   * @param deviceId
   */
  public deRegisterPush(deviceId) {
    // ...
  }

}

在我的单元测试中，我希望能够断言init()和on()方法已被调用，但我总是收到一个错误，说PushNotification未定义，所以我希望有人能够告诉我如何访问或注入它以某种方式进入组件？

我的测试文件如下：

// Core files and modules
import {
  TestBed,
  ComponentFixture
} from '@angular/core/testing';
import {
  NO_ERRORS_SCHEMA
} from '@angular/core';
import {
  App,
  AlertController,
  Events,
  Platform,
  Config
} from 'ionic-angular';

import {
  ViewController,
  Slides
} from 'ionic-angular';
import {
  mockOpportunityProvider,
  mockPushProvider,
  mockAuth,
  mockAppPlatform,
  mockPlatform,
  mockEvents,
  presentableControllerMock
} from '../../mocks';

import {
  OpportunityProvider
} from '../../providers/opportunity/opportunity.provider';
import {
  AuthProvider
} from '../../providers/auth/auth';
import {
  ProfileComponent
} from '../../pages/profile/profile.component';
import {
  PushProvider
} from '../../providers/push/push.provider';

// Pages
import {
  PushComponent
} from './push.component';
import {
  OpportunityComponent
} from '../../pages/opportunity/opportunity.component';

let component: PushComponent;
let fixture: ComponentFixture < PushComponent > ;

describe('Component: ProfileTemplateComponent', () => {
  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [],
      declarations: [PushComponent],
      providers: [{
          provide: OpportunityProvider,
          useClass: mockOpportunityProvider
        },
        {
          provide: AuthProvider,
          useClass: mockAuth
        },
        {
          provide: PushProvider,
          useClass: mockPushProvider
        },
        {
          provide: App,
          useClass: mockAppPlatform
        },
        ProfileComponent,
        {
          provide: Platform,
          useClass: mockPlatform
        },
        Config,
        {
          provide: AlertController,
          useClass: presentableControllerMock
        },
        {
          provide: Events,
          useClass: mockEvents
        }
      ],
      schemas: [NO_ERRORS_SCHEMA]

    }).compileComponents();

  });
  beforeEach(() => {
    fixture = TestBed.createComponent(PushComponent);
    component = fixture.componentInstance;
  });

  afterEach(() => {
    fixture.destroy();
    component = null;
  });

  // TODO - figure out how to access the PushNotification variable

  it('expect ngOnInit() to call  ', async() => {
    // ...
  });

  it('expect pushAction() to call nav.setRoot()', () => {
    // ...
  });

  it('expect pushAlert() to call alertCtrl.create() and present()', () => {
    // ...
  });

  it('expect resetBadge() to call _push.setApplicationIconBadgeNumber() if on cordova platform', () => {
    // ...
  });

  it('expect registerPush() to call pushProvider.register()', () => {
    // ...
  });

  it('expect deRegisterPush() to call pushProvider.deRegister()', () => {
    // ...
  });
});

提前致谢！