How to specify custom environment variables in Angular?

I would like to use another environment variable. In my case test. The reason is that I want to inject a http interceptor for my integration tests. This interceptor should only return a mocked response with predefined data and is used for testing only.

Is there an official angular-way?

So simply I want this app.module.ts:

    import { environment } from '../environments/environment';
    // ...

    export function CustomHttpProvider (backend: XHRBackend, options: RequestOptions) {
      return new HttpService(backend, options);
    }

    export function FakeHttpProvider (backend: XHRBackend, options: RequestOptions) {
      return new FakeHttpService(backend, options);
    }

    const HttpProvider = environment.test ? FakeHttpProvider : CustomHttpProvider;

    @NgModule({
      imports: [
        BrowserModule,
        HttpModule,
        BrowserAnimationsModule,

        // ... my modules + routing here
      ],
      declarations: [AppComponent],
      providers: [
        {
          provide: Http,
          useFactory: HttpProvider,
          deps: [XHRBackend, RequestOptions]
        }
      ],
      bootstrap: [AppComponent]
    })
    export class AppModule {}