BDDfy is a simple and fully featured BDD framework that makes it easy to turn your unit tests into living documentation. It works with any testing framework and test runner.
White is a framework for automating rich client applications. Tests/automation programs can be written in any .NET language and do not require the use of proprietary scripting languages.
Seleno is a framework for automating web applications that uses Selenium for browser automation. It implements Page Objects and Page Components for reading and writing web page data using strongly typed view models.
The Fluent MVC Testing library provides a fluent interface for creating terse and expressive tests against ASP.NET MVC controllers. The motivation behind this library is to provide a way to test MVC actions quickly and maintainably.
Convention over Configuration is a great way to cut down repetitive boilerplate code. ConventionTests is a code-only NuGet that provides a simple API to validate that your code adheres to your conventions.
In 2012 Mehdi Khalili and Michael Whelan started TestStack with BDDfy, a simple yet powerful and extensible BDD framework for .Net. that Mehdi had created, and Seleno, another .Net framework for automated UI testing with Selenium. Since then, they have been joined by Krzysztof Kozmic, Jake Ginnivan and Rob Moore and the White, Fluent MVC Testing, and Convention Tests projects have been added.
The goal of TestStack is to provide frameworks that support agile teams of developers, testers, and customers develop software in a "test first" approach (aligning with the left side of Marick's Quadrant). These tests promote the "testing as design" mindset, and tend to be automated. Things like unit and integration tests, acceptance tests, and UI tests and methodologies like Behaviour Driven Development and Acceptance Test Driven Development.
We aspire to have comprehensive documentation for all of our projects, but we can always use help. If you would like to contribute please read Contributing to TestStack for more information.
Jason Roberts has a couple of awesome Pluralsight courses about TestStack that will accelerate your learning.
Krzysztof Koźmic spoke about ConventionTests at NDC 2012. You can find the slides here and the introductory blog post here.