I think the point that you don't understand is that unit testing frameworks like NUnit (and the like) will help you in automating small to medium-sized tests. Usually you can run the tests in a GUI (that's the case with NUnit, for instance) by simply clicking a button and then - hopefully - see the progress bar stay green. If it turns red, the framework shows you which test failed and what exactly went wrong. In a normal unit test, you often use assertions, e.g. Assert.AreEqual(expectedValue, actualValue, "some description") - so if the two values are unequal you will see an error saying "some description: expected <expectedValue> but was <actualValue>".

总之，单元测试将使测试更快，对开发人员来说更舒服。您可以在提交新代码之前运行所有的单元测试，这样就不会中断同一项目中其他开发人员的构建过程。

单元测试，粗略地说，就是在与测试代码隔离的情况下测试代码。我想到的直接优势是:

测试的运行变得自动化和可重复 您可以在更细粒度的级别上进行测试，而不是通过GUI进行点击测试

请注意，如果您的测试代码写入文件、打开数据库连接或在网络上执行某些操作，则更适合将其归类为集成测试。集成测试是一件好事，但不应将其与单元测试混淆。单元测试代码应该简短、简单且易于执行。

另一种看待单元测试的方法是先编写测试。这被称为测试驱动开发(简称TDD)。TDD带来了额外的优势:

您不需要编写推测性的“我将来可能需要这个”代码——只要能够通过测试即可 您编写的代码总是会被测试覆盖 通过先编写测试，您不得不考虑如何调用代码，从长远来看，这通常会改善代码的设计。

如果你现在还没有做单元测试，我建议你现在就开始做。找一本好书，实际上任何xUnit-book都可以，因为它们之间的概念可以很好地转换。

有时编写单元测试会很痛苦。当出现这种情况时，试着找个人来帮助你，并抵制住“只写该死的代码”的诱惑。单元测试很像洗碗。这并不总是令人愉快的，但它让你的比喻厨房保持干净，而你真的希望它干净。：）

编辑:我想到了一个误解，虽然我不确定它是否普遍。我曾听一个项目经理说过，单元测试让团队把所有的代码都写了两次。如果它看起来和感觉是那样的，那么，你做错了。编写测试通常不仅可以加快开发速度，而且还为您提供了一个方便的“现在我完成了”指示器，否则您就不会有这个指示器。

在单元测试和TDD的哲学优势方面，这里有一些关键的“灯泡”观察，这些观察在我试探性地走上TDD启蒙之路的第一步时打动了我(没有原创或一定是新闻)……

TDD does NOT mean writing twice the amount of code. Test code is typically fairly quick and painless to write and is a key part of your design process and critically. TDD helps you to realize when to stop coding! Your tests give you confidence that you've done enough for now and can stop tweaking and move on to the next thing. The tests and the code work together to achieve better code. Your code could be bad / buggy. Your TEST could be bad / buggy. In TDD you are banking on the chances of BOTH being bad / buggy being fairly low. Often its the test that needs fixing but that's still a good outcome. TDD helps with coding constipation. You know that feeling that you have so much to do you barely know where to start? It's Friday afternoon, if you just procrastinate for a couple more hours... TDD allows you to flesh out very quickly what you think you need to do, and gets your coding moving quickly. Also, like lab rats, I think we all respond to that big green light and work harder to see it again! In a similar vein, these designer types can SEE what they're working on. They can wander off for a juice / cigarette / iphone break and return to a monitor that immediately gives them a visual cue as to where they got to. TDD gives us something similar. It's easier to see where we got to when life intervenes... I think it was Fowler who said: "Imperfect tests, run frequently, are much better than perfect tests that are never written at all". I interprete this as giving me permission to write tests where I think they'll be most useful even if the rest of my code coverage is woefully incomplete. TDD helps in all kinds of surprising ways down the line. Good unit tests can help document what something is supposed to do, they can help you migrate code from one project to another and give you an unwarranted feeling of superiority over your non-testing colleagues :)

这篇演讲很好地介绍了测试所需要的所有内容。

使用Testivus。你需要知道的都在那里:)

这回答了为什么您应该进行单元测试。

下面的三个视频涵盖了javascript中的单元测试，但一般原则适用于大多数语言。

单元测试:现在的几分钟将节省几小时后- Eric Mann - https://www.youtube.com/watch?v=_UmmaPe8Bzc

JS单元测试(非常好)- https://www.youtube.com/watch?v=-IYqgx8JxlU

编写可测试的JavaScript - https://www.youtube.com/watch?v=OzjogCFO4Zo

Now I'm just learning about the subject so I may not be 100% correct and there's more to it than what I'm describing here but my basic understanding of unit testing is that you write some test code (which is kept separate from your main code) that calls a function in your main code with input (arguments) that the function requires and the code then checks if it gets back a valid return value. If it does get back a valid value the unit testing framework that you're using to run the tests shows a green light (all good) if the value is invalid you get a red light and you then can fix the problem straight away before you release the new code to production, without testing you may actually not have caught the error.

So you write tests for you current code and create the code so that it passes the test. Months later you or someone else need to modify the function in your main code, because earlier you had already written test code for that function you now run again and the test may fail because the coder introduced a logic error in the function or return something completely different than what that function is supposed to return. Again without the test in place that error might be hard to track down as it can possibly affect other code as well and will go unnoticed.

Also the fact that you have a computer program that runs through your code and tests it instead of you manually doing it in the browser page by page saves time (unit testing for javascript). Let's say that you modify a function that is used by some script on a web page and it works all well and good for its new intended purpose. But, let's also say for arguments sake that there is another function you have somewhere else in your code that depends on that newly modified function for it to operate properly. This dependent function may now stop working because of the changes that you've made to the first function, however without tests in place that are run automatically by your computer you will not notice that there's a problem with that function until it is actually executed and you'll have to manually navigate to a web page that includes the script which executes the dependent function, only then you notice that there's a bug because of the change that you made to the first function.

重申一下，在开发应用程序时运行测试将在编写代码时发现这类问题。如果没有适当的测试，你必须手动检查整个应用程序，即使这样也很难发现错误，你天真地将其发送到生产环境中，一段时间后，好心的用户会给你发送错误报告(这不会像你在测试框架中的错误消息那样好)。

It's quite confusing when you first hear of the subject and you think to yourself, am I not already testing my code? And the code that you've written is working like it is supposed to already, "why do I need another framework?"... Yes you are already testing your code but a computer is better at doing it. You just have to write good enough tests for a function/unit of code once and the rest is taken care of for you by the mighty cpu instead of you having to manually check that all of your code is still working when you make a change to your code.

此外，如果你不想进行单元测试，你也不必进行单元测试，但随着你的项目/代码库开始变得越来越大，引入错误的可能性也在增加，这是值得的。

首先，无论是谈论单元测试还是其他类型的自动化测试(集成、加载、UI测试等)，与您所建议的关键区别在于它是自动化的、可重复的，并且不需要消耗任何人力资源(=没有人需要执行测试，它们通常按下按钮就可以运行)。