anchor.diff:      A query predicate receives a `DebugElement` and returns `true` if the element meets the selection criteria.
   
       **predicate**是返回布尔值的函数。
  -    predicate查询接受`DebugElement`，如果元素符合选择条件便返回`true`。
  +    predicate查询接受`DebugElement`参数，如果元素符合选择条件便返回`true`。
       
   :marked
     The **`By`** class is an Angular testing utility that produces useful predicates. 
  
positive.code:   `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。
    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 
  
negative.code:   something to cure now rather than later when it becomes expensive to fix.
  
    1. 测试**暴露**设计和实现可能出现的错误。测试从很多角度为代码亮出警报灯。当应用程序很难被测试时，
    其根本原因一般都是设计缺陷，这种缺陷最好立刻被修正，不要等到它变得很难被修复的时候才行动。
  
    This chapter assumes that you know something about testing. Don't worry if you don't. 
    There are plenty of books and online resources to get up to speed.
  