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.

偶尔，我自己或我的同事会花几个小时来研究一个不太明显的错误，一旦发现了错误的原因，90%的情况下代码都没有经过单元测试。单元测试并不存在，因为开发人员为了节省时间而偷工减料，但随后却失去了这一点和更多的调试。

花少量的时间来编写单元测试可以节省未来调试的时间。

我曾多次尝试单元测试，我仍然相信，考虑到我的情况，这是值得的。

我开发网站，其中很多逻辑涉及在数据库中创建、检索或更新数据。当我为了单元测试的目的而尝试“模拟”数据库时，它变得非常混乱，似乎有点毫无意义。

当我围绕业务逻辑编写单元测试时，从长远来看它从未真正帮助过我。因为我主要独自从事项目工作，我倾向于直观地知道哪些代码区域可能会受到我所从事的工作的影响，并且我手动测试这些区域。我希望尽可能快地向客户交付解决方案，而单元测试通常看起来是浪费时间。我列出了手动测试，并亲自完成它们，并在执行过程中标记它们。

我可以看到，当一个开发团队在一个项目中工作并互相更新代码时，这可能是有益的，但即使这样，我认为如果开发人员具有高质量，良好的沟通和编写良好的代码通常就足够了。

单元测试的全部意义在于使测试变得简单。这是自动的。“make test”就完成了。如果您面临的问题之一是难以测试代码，那么这就是使用单元测试的最佳理由。

就在今天，我不得不更改一个类，之前已经为其编写了单元测试。 测试本身写得很好，包括我甚至没有想过的测试场景。 幸运的是，所有测试都通过了，我的更改很快得到了验证，并自信地放到了测试环境中。

Unit Testing is one of the most adopted methodologies for high quality code. Its contribution to a more stable, independent and documented code is well proven . Unit test code is considered and handled as an a integral part of your repository, and as such requires development and maintenance. However, developers often encounter a situation where the resources invested in unit tests where not as fruitful as one would expect. In an ideal world every method we code will have a series of tests covering it’s code and validating it’s correctness. However, usually due to time limitations we either skip some tests or write poor quality ones. In such reality, while keeping in mind the amount of resources invested in unit testing development and maintenance, one must ask himself, given the available time, which code deserve testing the most? And from the existing tests, which tests are actually worth keeping and maintaining? See here