MSTest is essentially NUnit slightly reworked, with a few new features (such as assembly setup and teardown, not just fixture and test level), and missing some of the best bits (such as the new 2.4 constraint syntax). NUnit is more mature, and there is more support for it from other vendors; and of course since it's always been free (whereas MSTest only made it into the Professional version of Visual Studio 2008, and before that it was in way more expensive SKUs), and most ALT.NET projects use it.

话虽如此，还是有一些公司非常不愿意使用没有微软标签的东西，尤其是OSS代码。因此，拥有官方的微软测试框架可能是这些公司需要进行测试的动机;老实说，重要的是测试，而不是你使用什么工具(使用Tuomas Hietanen的代码，你几乎可以让你的测试框架可互换)。

首先我想纠正一个错误的说法:你可以使用命令行在Visual Studio之外运行MSTest。尽管一些CI工具，如TeamCity，对NUnit有更好的支持(可能会随着MSTest变得更流行而改变)。

在我目前的项目中，我们两者都使用，唯一的大区别是，我们发现MSTest总是作为32位运行，而NUnit运行为32位或64位测试，这只在你的代码使用32/64位依赖的本机代码时才重要。

我已经使用NUnit两年了。一切都很好，但是我不得不说Visual Studio中的单元测试系统非常好，因为它在GUI中，可以更容易地对私有函数进行测试，而不必搞得乱七八糟。

此外，Visual Studio的单元测试允许你做覆盖和其他NUnit单独不能做的事情。

如果你正在考虑MSTest或NUnit，那么我建议你看看MbUnit。我的理由是

TestDriven.Net compatibility. Nothing beats have TestDriven.Net.ReRunWithDebugger bound to a keyboard combination. The Gallio framework. Gallio is a test runner like NUnit's. The only difference is it doesn't care if you wrote your tests in NUnit, MSTest, xUnit or MbUnit. They all get run. Compatibility with NUnit. All features in NUnit are supported by MbUnit. I think you don't even need to change your attributes (will have to check that), just your reference and usings. Collection asserts. MbUnit has more Assert cases, including the CollectionAssert class. Basically you no longer need to write your own tests to see if two collections are the same. Combinatorial tests. Wouldn't it be cool if you could supply two sets of data and get a test for all the combinations of data? It is in MbUnit.

我最初选择MbUnit是因为它的[RowTest ....我找不到一个回去的理由。我把我所有的活动测试套件从NUnit移过来，再也没有回头。从那时起，我已经将两个不同的开发团队转换为收益。

Visual Studio 2008内置单元测试框架的优点/变化:

The 2008 version now is available in professional editions (before it required expensive versions of Visual Studio, and this is just for developer unit testing) that left a lot of developers with the only choice of open/external testing frameworks. Built-in API supported by a single company. Use the same tools to to run and create tests (you may run them using the command line also MSTest). Simple design (granted without a mock framework, but this is a great starting point for many programmers). Long term support granted (I still remember what happened to NDoc, and I don't want to commit to a testing framework that might not be supported in five years, but I still consider NUnit a great framework). If using Team Foundation Server as your backend, you can create work items or bugs with the failed test data in a simple fashion.

我收到消息说“NUnit文件结构比VSTest更丰富”… 当然，如果你更喜欢NUnit的文件结构，你可以使用这个解决方案的另一种方式，像这样(NUnit→Visual Studio):

 #if !MSTEST
     using NUnit.Framework;
 #else
     using Microsoft.VisualStudio.TestTools.UnitTesting;
     using TestFixture = Microsoft.VisualStudio.TestTools.UnitTesting.TestClassAttribute;
     using Test = Microsoft.VisualStudio.TestTools.UnitTesting.TestMethodAttribute;
     using SetUp = Microsoft.VisualStudio.TestTools.UnitTesting.TestInitializeAttribute;
     using TearDown = Microsoft.VisualStudio.TestTools.UnitTesting.TestCleanupAttribute;
 #endif

或任何其他转换…:-)这里的用法只是编译器的别名。