我不知道。很多地方不做单元测试，但是代码质量很好。微软做单元测试，但是比尔·盖茨在他的演示中出现了蓝屏。

你想说服谁?工程师还是经理?如果你试图说服你的工程师同事，我认为你最好的办法是迎合他们的愿望，让他们做出高质量的软件。有许多研究表明，它能发现漏洞，如果他们关心做好工作，这对他们来说就足够了。

如果您试图说服管理层，您将很可能不得不做一些成本/收益推理，说明未检测到的缺陷的成本大于编写测试的成本。一定要把不可转化的成本也包括在内，比如失去客户的信心等等。

单元测试非常值得最初的投资。自从几年前开始使用单元测试以来，我发现了一些真正的好处:

回归测试消除了恐惧 对代码进行更改(什么都没有 就像看到代码的温暖光芒 每次有变化，要么工作，要么爆发 了) 以下的可执行代码示例 其他团队成员(包括你自己) 6个月的时间…) 无情的重构——这是令人难以置信的回报，试试吧!

代码片段可以极大地帮助减少创建测试的开销。创建能够在几秒钟内创建类大纲和相关单元测试fixture的代码片段并不困难。

单元测试很像去健身房。你知道这对你有好处，所有的争论都有意义，所以你开始锻炼。刚开始有一种冲动，这很好，但几天后你开始怀疑是否值得这样做。你每天花一个小时换衣服，在仓鼠转轮上跑步，你不确定除了腿和手臂疼痛之外，你真的得到了什么。

然后，也许一两周后，就在疼痛消失的时候，一个重要的截止日期开始来临。你需要把醒着的每一个小时都用来完成“有用的”工作，所以你要去掉无关紧要的事情，比如去健身房。你改掉了这个习惯，当截止日期结束的时候，你又回到了起点。如果你设法回到健身房，你会觉得和你第一次去的时候一样酸痛。

You do some reading, to see if you're doing something wrong. You begin feel a little bit of irrational spite toward all the fit, happy people extolling the virtues of exercise. You realize that you don't have a lot in common. They don't have to drive 15 minutes out of the way to go to the gym; there is one in their building. They don't have to argue with anybody about the benefits of exercise; it is just something everybody does and accepts as important. When a Big Deadline approaches, they aren't told that exercise is unnecessary any more than your boss would ask you to stop eating.

所以，回答你的问题，单元测试通常是值得付出努力的，但是所需的努力量对每个人来说都不一样。如果你在一家不重视代码质量的公司处理意大利面条式的代码库，那么单元测试可能需要付出巨大的努力。(许多经理会歌颂单元测试，但这并不意味着他们会在关键时刻支持单元测试。)

如果你正试图将单元测试引入到你的工作中，并且没有看到你所期待的所有阳光和彩虹，不要责怪自己。你可能需要找一份新工作来真正让单元测试为你工作。

thetalkingwalnut问道: 有什么好方法可以让团队中持怀疑态度的开发人员相信单元测试的价值?

Everyone here is going to pile on lots of reasons out of the blue why unit testing is good. However, I find that often the best way to convince someone of something is to listen to their argument and address it point by point. If you listen and help them verbalize their concerns, you can address each one and perhaps convert them to your point of view (or at the very least, leave them without a leg to stand on). Who knows? Perhaps they will convince you why unit tests aren't appropriate for your situation. Not likely, but possible. Perhaps if you post their arguments against unit tests, we can help identify the counterarguments.

It's important to listen to and understand both sides of the argument. If you try to adopt unit tests too zealously without regard to people's concerns, you'll end up with a religious war (and probably really worthless unit tests). If you adopt it slowly and start by applying it where you will see the most benefit for the least cost, you might be able to demonstrate the value of unit tests and have a better chance of convincing people. I realize this isn't as easy as it sounds - it usually requires some time and careful metrics to craft a convincing argument.

单元测试是一种工具，就像任何其他工具一样，应该以这样一种方式进行应用，即收益(捕捉错误)大于成本(编写它们的工作)。如果它们没有意义，就不要使用它们，记住它们只是你工具库的一部分(例如检查、断言、代码分析器、形式化方法等)。我告诉开发者的是:

They can skip writing a test for a method if they have a good argument why it isn't necessary (e.g. too simple to be worth it or too difficult to be worth it) and how the method will be otherwise verified (e.g. inspection, assertions, formal methods, interactive/integration tests). They need to consider that some verifications like inspections and formal proofs are done at a point in time and then need to be repeated every time the production code changes, whereas unit tests and assertions can be used as regression tests (written once and executed repeatedly thereafter). Sometimes I agree with them, but more often I will debate about whether a method is really too simple or too difficult to unit test. If a developer argues that a method seems too simple to fail, isn't it worth taking the 60 seconds necessary to write up a simple 5-line unit test for it? These 5 lines of code will run every night (you do nightly builds, right?) for the next year or more and will be worth the effort if even just once it happens to catch a problem that may have taken 15 minutes or longer to identify and debug. Besides, writing the easy unit tests drives up the count of unit tests, which makes the developer look good. On the other hand, if a developer argues that a method seems too difficult to unit test (not worth the significant effort required), perhaps that is a good indication that the method needs to be divided up or refactored to test the easy parts. Usually, these are methods that rely on unusual resources like singletons, the current time, or external resources like a database result set. These methods usually need to be refactored into a method that gets the resource (e.g. calls getTime()) and a method that takes the resource as a argument (e.g. takes the timestamp as a parameter). I let them skip testing the method that retrieves the resource and they instead write a unit test for the method that now takes the resource as a argument. Usually, this makes writing the unit test much simpler and therefore worthwhile to write. The developer needs to draw a "line in the sand" in how comprehensive their unit tests should be. Later in development, whenever we find a bug, they should determine if more comprehensive unit tests would have caught the problem. If so and if such bugs crop up repeatedly, they need to move the "line" toward writing more comprehensive unit tests in the future (starting with adding or expanding the unit test for the current bug). They need to find the right balance.

重要的是要认识到单元测试并不是万能的，而且存在太多单元测试这样的事情。在我的工作场所，每当我们做一个经验教训，我不可避免地听到“我们需要写更多的单元测试”。管理层点头表示同意，因为“单元测试”==“好”这句话已经被灌输到他们的头脑中了。

However, we need to understand the impact of "more unit tests". A developer can only write ~N lines of code a week and you need to figure out what percentage of that code should be unit test code vs production code. A lax workplace might have 10% of the code as unit tests and 90% of the code as production code, resulting in product with a lot of (albeit very buggy) features (think MS Word). On the other hand, a strict shop with 90% unit tests and 10% production code will have a rock solid product with very few features (think "vi"). You may never hear reports about the latter product crashing, but that likely has as much to do with the product not selling very well as much as it has to do with the quality of the code.

Worse yet, perhaps the only certainty in software development is that "change is inevitable". Assume the strict shop (90% unit tests/10% production code) creates a product that has exactly 2 features (assuming 5% of production code == 1 feature). If the customer comes along and changes 1 of the features, then that change trashes 50% of the code (45% of unit tests and 5% of the production code). The lax shop (10% unit tests/90% production code) has a product with 18 features, none of which work very well. Their customer completely revamps the requirements for 4 of their features. Even though the change is 4 times as large, only half as much of the code base gets trashed (~25% = ~4.4% unit tests + 20% of production code).

我的观点是你必须传达你理解单元测试太少和太多之间的平衡——本质上你已经考虑了问题的两面。如果你能说服你的同事和/或你的管理层，你就获得了信誉，也许就有更好的机会赢得他们的信任。

多年来，我一直试图说服人们，他们需要为自己的代码编写单元测试。无论他们是先编写测试(如TDD)还是在编写功能之后，我总是试图向他们解释对代码进行单元测试的所有好处。几乎没有人反对我。你不能否认一些显而易见的事情，任何聪明的人都会看到单元测试和TDD的好处。

单元测试的问题在于它需要行为上的改变，而要改变人们的行为是非常困难的。用语言，你会让很多人同意你的观点，但你不会看到他们做事的方式有太多变化。

你必须通过行动来说服人们。你的个人成功会比你的争论吸引更多的人。如果他们看到你不只是在谈论单元测试或TDD，而是在做你鼓吹的事情，而且你是成功的，人们就会试图模仿你。

You should also take on a lead role because no one writes unit test right the first time, so you may need to coach them on how to do it, show them the way, and the tools available to them. Help them while they write their first tests, review the tests they write on their own, and show them the tricks, idioms and patterns you've learned through your own experiences. After a while, they will start seeing the benefits on their own, and they will change their behavior to incorporate unit tests or TDD into their toolbox.

改变不会在一夜之间发生，但只要有一点耐心，你就可能实现你的目标。