Top 20 NuGet unittesting Packages

It's what a Mocking Framework should be. Powerful. And it's the first of its kind.
It's faking amazing! The easy mocking framework for .NET that works great in C# and VB.NET alike. No need to know the difference between a stub, a mock or a spy, everything's a fake! The easy to use, refactoring friendly API makes faking a breeze.
The most powerful free mocking library available for .NET developers.
A Serilog sink that correlates log events with the code that produced them, enabling unit testing of log output.
Moq is the most popular and friendly mocking framework for .NET
Contributed features and third-party integration for Moq.
.NET port of Hamcrest, a matcher library with some extra matchers
Through a fluent, extensible interface, NBuilder allows you to rapidly create test data, automatically assigning values to properties and public fields that are one of the built in .NET data types (e.g. ints and strings). NBuilder allows you to override for properties you are interested in using lam...
Dynamic mocking framework for .NET
Foq is a lightweight thread-safe mocking library for F#, C#, and VB with a similar API to Moq.
Support for unit testing of libraries based on the re-linq SQL Backend.
Speed up your unit test writing by using this helper that leverages AutoMocker to automatically mock dependencies.
A .NET library for using MSTest (and Moq) on top of the ChannelAdam Test Framework.
A context/specification test framework, heavily inspired by RSpec
A .NET library that provides helpers for using Moq on top of the ChannelAdam.TestFramework.
A super simple C# script test runner
Microsoft.VisualStudio.TestTools.UnitTesting to Xunit proxy
MbUnit supports creating tests dynamically at run time. By creating a wrapper that exposes FSpec tests as MbUnit dynamic tests, tools that integrate with MbUnit can be allowed to see FSpec tests.
Record your code's execution and replay it later
StatLight: Tool for executing Silverlight test xap packages or dll assemblies locally during development and in a continuous integration environment.