> Test-driven development (TDD) is a software development process that relies on the repetition of a very short development cycle: requirements are turned into very specific test cases, then the software is improved to pass the new tests, only.
>
> --- [Test-driven development. (2016, November 20). In Wikipedia, The Free Encyclopedia. Retrieved 23:45, November 20, 2016](https://en.wikipedia.org/w/index.php?title=Test-driven_development&oldid=750634597)
通常不使用连字符,而是使用 em 破折号(U + 2014)。许多 Markdown 解析器支持 Unicode,这意味着您可以直接编写 em 破折号,而不必使用 HTML 实体。直接编写这样的字符可以提高可读性,更多的工具将知道您想要什么,而不是惊慌,您的文档可能更加便携,因为您没有将自己绑定到 HTML。