One of the best things about unit testing is that your code will become easier to test as you do it. Preexisting code created without tests is always a challenge because since they weren't meant to be unit-tested, it's not rare to have a high level of coupling between classes, hard-to-configure objects inside your class - like an e-mail sending service reference - and so on. But don't let this bring you down! You'll see that your overall code design will become better as you start to write unit-tests, and the more you test, the more confident you'll become on making even more changes to it without fear of breaking you application or introducing bugs.

There are several reasons to unit-test your code, but as time progresses, you'll find out that the time you save on testing is one of the best reasons to do it. In a system I've just delivered, I insisted on doing automated unit-testing in spite of the claims that I'd spend way more time doing the tests than I would by testing the system manually. With all my unit tests done, I run more than 400 test cases in less than 10 minutes, and every time I had to do a small change in the code, all it took me to be sure the code was still working without bugs was ten minutes. Can you imagine the time one would spend to run those 400+ test cases by hand?

当涉及到自动化测试——无论是单元测试还是验收测试——每个人都认为编写可以手动完成的代码是浪费精力，有时这是真的——如果你计划只运行一次测试的话。自动化测试最好的部分是，您可以毫不费力地运行它们几次，并且在第二次或第三次运行之后，您所浪费的时间和精力已经得到了补偿。

最后一个建议是，不仅要对代码进行单元测试，还要先进行测试(详见TDD和BDD)。

单元测试可以帮助您以更少的错误发布软件，同时降低总体开发成本。您可以点击链接阅读更多关于单元测试的好处

单元测试适用于QA人员或你的经理，而不是你;所以绝对不值得。

您应该专注于编写正确的代码(不管这意味着什么)，而不是测试用例。让其他人去担心吧。

Unit testing helps a lot in projects that are larger than any one developer can hold in their head. They allow you to run the unit test suite before checkin and discover if you broke something. This cuts down a lot on instances of having to sit and twiddle your thumbs while waiting for someone else to fix a bug they checked in, or going to the hassle of reverting their change so you can get some work done. It's also immensely valuable in refactoring, so you can be sure that the refactored code passes all the tests that the original code did.

单元测试的好处之一是可预测性。

在单元测试之前，我可以非常准确地预测编写代码所需的时间，但无法预测调试所需的时间。

现在，因为我可以计划将要编写什么测试，所以我知道编码需要多长时间，并且在编码结束时，系统已经调试好了!这为开发过程带来了可预见性，消除了许多压力，但仍然保留了所有的乐趣!!

如果你正在使用NUnit，一个简单而有效的演示就是在他们面前运行NUnit自己的测试套件。看到一个真正的测试套件对代码库进行测试，胜过千言万语……