anchor.diff:    albeit at greater depth in the element tree than before.
   
     当然，创建`TestHostComponent`有创建`DashboardHeroComponent`的副作用，因为后者出现在前者的模板中。
  -  英雄元素（`heroEl`)的查询语句仍然可以在测试DOM中找到它，尽管元素数比以前更深。
  +  英雄元素（`heroEl`)的查询语句仍然可以在测试DOM中找到它，尽管元素树比以前更深。
     
     The tests themselves are almost identical to the stand-alone version
   
  
positive.code:   它注入服务到测试函数，以供修改、监视和操纵。
  
    The `inject` function has two parameters
    `inject`函数有两个参数：
  
    1. an array of Angular dependency injection tokens
  
negative.code:   It also injects the `HeroService` but faking that is a [familiar story](#component-with-async-servic).
    The `Router` has a complicated API and is entwined with other services and application pre-conditions.
  
    它同时还注入了`HeroService`，但是我们已经知道如何[伪造](#component-with-async-servic)它。
    `Router`的API非常复杂，并且它缠绕了其它服务和许多应用的先决条件。
  
    Fortunately, the `DashboardComponent` isn't doing much with the `Router`
  
  