it('merges imports and exports', () => {
      const TOKEN = new InjectionToken<string>('TOKEN');
      @NgModule({
        providers: [{provide: TOKEN, useValue: 'provided from A'}],
      })
      class AModule {
      }
      @NgModule({
        providers: [{provide: TOKEN, useValue: 'provided from B'}],
      })
      class BModule {
      }

      @NgModule({
        imports: [AModule],
        exports: [BModule],
      })
      class CModule {
      }

      const injector = createInjector(CModule);
      expect(injector.get(TOKEN)).toEqual('provided from B');
    });

 expect(() => createInjector(AModule))

 beforeEach(() => { injector = createInjector(AotModule); });