NUnit, XUnit.net, QUnit, Jasmine, Chutzpah are all supported in the Visual Studio 11 Beta along with MSUnit, promising better choice and over-all unit-testing experience for developers. And the list is expected to get bigger towards the final release of VS 11.
Microsoft has worked with the community to build better Visual Studio drivers for the above mentioned testing frameworks. Developers can choose to stick with the in-built MSUnit framework, or decide to install these drivers and have in-built-like experience even with these open source tools. These adapters can also be configured to work with the build server like any other extension. You can see the full list of supported frameworks along with their download links on ScottGu’s update.
However, just like other third-party extensions, they are not available with the express SKUs of Visual Studio.
Even though Visual Studio shipped with MSUnit since earlier versions, a lot of .NET developers prefer open source tools such as NUnit and XUnit for unit testing their code. Besides, with the increasing use of JavaScript in web applications, frameworks such as Jasmine and QUnit too are being used more frequently. It is common for developers today to be working with multiple tools outside Visual Studio to have good test coverage and/or use other bridging tools (like TestDriven.NET and Chutzpah) for VS-integration. With VS 11 having in-built support for these frameworks though, it should be a much smoother experience.
In the big picture, this fits into the trend of Microsoft working closer with open source communities. In recent times, we have seen several steps such as open-sourcing certain .NET technology bits and shipping JQuery and Modernizr with Visual Studio. In fact there is a dedicated website that Microsoft maintains about their open source initiatives with a large list of projects, most of them hosted on CodePlex.