anchor.diff:    `TestBed.configureTestingModule` takes an `@NgModule`-like metadata object.
     This one simply declares the component to test, `BannerComponent`.
   
  -  `TestBed.configureTestingModule`接受像`@NgModule`元素据的对象。
  +  `TestBed.configureTestingModule`接受像`@NgModule`元数据的对象。
     这里的对象仅仅声明了要测试的组件`BannerComponent`。
     
     It lacks `imports` because (a) it extends the default testing module configuration which 
  
positive.code:   The `WelcomeComponent` displays a welcome message to the logged in user.
    It knows who the user is based on a property of the injected `UserService`:
  
    组件经常有服务依赖。`WelcomeComponent`为登陆的用户显示一条欢迎信息。它从注入的`UserService`的属性知道用户的身份：
    
  +makeExample('testing/ts/app/welcome.component.ts', '', 'app/welcome.component.ts')(format='.')
  :marked
  
negative.code:   Finally, the setup assigns the DOM element from the `DebugElement` **`nativeElement`** property to `el`.
    The tests will assert that `el` contains the expected title text.
  
    最后，这个配置指定`DebugElement`中的**`nativeElement`**DOM元素到属性`el`。
    测试将判断`el`是否包含期待的标题文本。
  
    ### The tests
  