anchor.diff:    Yet we were able to load and test the application’s `Hero` interface.
   
     往回看`unit-tests.html`，我们认识到自己还没加载过Angular库。
  -  但我们甚至都已经能加载应用中`Hero`接口的测试了。
  +  但是我们可以加载和测试应用中`Hero`接口的测试了。
   
     **We were lucky!**  The `Hero` interface has no dependence on Angular.
     If it had depended on Angular, we’d still be staring at the Jasmine “big-time fail” screen:
  
positive.code: 
    But it's not always feasible. For instance, sometimes we need to write tests for existing functionality, like what we're about to do with the rest of Tour of Heroes.
  
    但这也并不总是可行的。比如，优势我们需要为现有功能写测试，就像我们即将对《英雄指南》的其余部分所做的那样。
  
    If we are writing new code though, writing tests might just be what we need to help us track our progress and keep the end result in sight at all times.
  
  
negative.code: 
    We can make our own `my-uppercase` pipe that does exactly the same as the `uppercase` pipe and test that.
  
    我们可以做一个自己的`my-uppercase`管道并测试它，该管道的功能和`uppercase`管道完全相同。
  
    Since we're getting ready to write some code we want to test, let's take this opportunity to talk just a little bit about [Test Driven Development](https://en.wikipedia.org/wiki/Test-driven_development). There's a lot written about this topic so we don't want to have an exhaustive description here, but rather a practical application.
  
  