anchor.diff:    On the other hand, why burden simple service tests with added complexity?
   
     它们有类似的行数。
  -  但是，依赖Angular的版本有用更多移动部分，包括一些工具函数（`async`和`inject`).
  +  但是，依赖Angular的版本有更多活动的部分，包括一些工具函数（`async`和`inject`).
     两种方法都可行，而且如果你为了某些原因使用Angular测试工具，也并没有什么问题。
     反过来，为什么要为简单的服务测试程序添加复杂度呢？
   
  
positive.code: 
    Testing applications with the help of the Angular testing utilities is the main focus of this chapter.
  
    使用Angular测试工具测试应用程序时本章的重点。
  
    However, it's often more productive to explore the inner logic of application classes
    with _isolated_  unit tests that don't depend upon Angular.
  
negative.code:   But feel free to exploit the `nativeElement` when that seems easier or more clear than the abstraction.
  
    * 在缺乏浏览器时，`DebugElement.styles`提供对元素样式的访问。
    但是，请随意使用`nativeElement`，它可能更加容易、更加清晰。
  
    * Angular adds a directive to the injector of the element to which it is applied. 
    The test for the default color uses the injector of the 2nd `<h2>` to get its `HighlightDirective` instance
  