anchor.diff:  :marked
     Notable features of this stub:
   
  -  这个类有下列值得注意的特征：
  +  这个stub类有下列值得注意的特征：
   
     * The stub implements only two of the `ActivatedRoute` capabilities: `params` and `snapshot.params`.
   
  -  * 它只实现`ActivatedRoute`的两个功能：`params`和`snapshot.params`。
  +  * 这个stub类只实现`ActivatedRoute`的两个功能：`params`和`snapshot.params`。
   
     * <a href="https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/subjects/behaviorsubject.md" target="_blank">_BehaviorSubject_</a> 
     drives the stub's `params` _Observable_ and returns the same value to every `params` subscriber until it's given a new value.
   
     * <a href="https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/subjects/behaviorsubject.md" target="_blank">_BehaviorSubject_</a>
  -  驱使它的`params`可观察对象，并为每个`params`的订阅者返回同样的值，直到它接受到新值。  
  +  驱使这个stub类的`params`可观察对象，并为每个`params`的订阅者返回同样的值，直到它接受到新值。  
   
     * The `HeroDetailComponent` chain its expressions to this stub `params` _Observable_ which is now under the tester's control.
   
  -  * `HeroDetailComponent`链接它的表达式到它的`params`可观察对象，该对象现在被测试者所控制。
  +  * `HeroDetailComponent`链接这个stub类的表达式到它的`params`可观察对象，该对象现在被测试者所控制。
   
     * Setting the `testParams` property causes the `subject` to push the assigned value into `params`.
      That triggers the `HeroDetailComponent` _params_ subscription, described above, in the same way that navigation does.
  
positive.code: 
    The tests need access to the (stub) `UserService` injected into the `WelcomeComponent`.
  
    测试需要访问被注入到`WelcomeComponent`中的的`UserService`（stub）。
  
    Angular has a hierarchical injection system.
    There can be injectors at multiple levels, from the root injector created by the `TestBed`
  
negative.code: :marked
    The first is a sanity test; it confirms that the stubbed `UserService` is called and working.
  
    第一个测试是合法测试，它确认这个被模拟的`UserService`是否被调用和工作正常。
    
  .l-sub-section
    :marked
  