anchor.diff:    The safest way to get the injected service, the way that **_always works_**, 
     is to **get it from the injector of the _component-under-test_**.
     The component injector is a property of the fixture's `DebugElement`.
  +
  +  最安全的获取注入的服务和**总是有效**的方法，是**从被测试的组件的注入器获取**。
  +  组件注入器是fixture的`DebugElement`的一个属性。
  +
   +makeExample('testing/ts/app/welcome.component.spec.ts', 'injected-service', 'WelcomeComponent\'s injector')(format='.')
   
   #testbed-get
   :marked
  +  ### _TestBed.get_
  +
     ### _TestBed.get_
   
     You _may_ also be able to get the service from the root injector via `TestBed.get`.
  
positive.code: :marked
    The command compiles the application and test code and starts karma.
    Both processes watch pertinent files, write messages to the console, and re-run when they detect changes.
  .l-sub-section
    :marked
      The QuickStart development path defined the `test` command in the `scripts` section of npm's `package.json`.
      The Angular CLI has different commands to do the same thing. Adjust accordingly.
  :marked
    After a few moments, karma opens a browser and starts writing to the console.
  figure.image-display
    img(src='/resources/images/devguide/testing/karma-browser.png' style="width:400px;" alt="Karma browser")
  :marked
  
negative.code:   But it only works when Angular injects the component with the service instance in the test's root injector.
    Fortunately, in this test suite, the _only_ provider of `UserService` is the root testing module, 
    so it is safe to call `TestBed.get` as follows:
  
    你**可以**通过`TestBed.get`方法来从根注入器中获取服务。
    它更容易被记住，也更加简介。
    But it only works when Angular injects the component with the service instance in the test's root injector.
    Fortunately, in this test suite, the _only_ provider of `UserService` is the root testing module, 
    so it is safe to call `TestBed.get` as follows:
    
  +makeExample('testing/ts/app/welcome.component.spec.ts', 'inject-from-testbed', 'TestBed injector')(format='.')
  .l-sub-section
    :marked
  