anchor.diff:    只有selected事件的测试不一样。它确保被选择的`DashboardHeroComponent`英雄确实通过事件绑定被传递到宿主组件。
   
   a(href="#top").to-top Back to top
  -a(href="#top").to-top 返回顶部
  +a(href="#top").to-top 回到顶部
   
   .l-hr
   
  
positive.code:   Clicking the anchor should trigger the `onClick` method which sets the telltale `navigatedTo` property.
    Tests can inspect that property to confirm the expected _click-to-navigation_ behavior.
  
  #by-directive
  #inject-directive
  :marked
    ### _By.directive_ and injected directives
  
    A little more setup triggers the initial data binding and gets references to the navigation links:
  +makeExample('testing/ts/app/app.component.spec.ts', 'test-setup', 'app/app.component.spec.ts (test setup)')(format='.')
  :marked
    Two points of special interest:
  
    1. You can locate elements _by directive_, using `By.directive`, not just by css selectors.
  
    1. You can use the component's dependency injector to get an attached directive because 
    Angular always adds attached directives to the component's injector.
  
  #app-component-tests
  :marked
    Here are some tests that leverage this setup:
  +makeExample('testing/ts/app/app.component.spec.ts', 'tests', 'app/app.component.spec.ts (selected tests)')(format='.')
  .l-sub-section
    :marked
  
negative.code:   The _only_ declarations are the _component-under-test_ (`AppComponent`) and the `RouterLinkStubDirective` 
    that contributes actively to the tests.
    The [tests in this example](#app-component-tests) are unchanged.
  
    这里**唯一**声明的是**被测试的组件**(`AppComponent`)和测试需要的`RouterLinkStubDirective`。
    没有改变任何[原测试](#app-component-tests)。
  
  .alert.is-important
    :marked
  