Top 20 NuGet unittesting Packages

Deleporter - Simple Cross Process Stubbing. Facilitates stubbing out dependencies when running automated browser tests against ASP.Net. Use in conjunction with your favorite mocking/IOC frameworks. Deleporter will teleport mock objects (or any arbitrary delegates) into a remote ASP.Net application, ...
Augments Microsoft's Visual Studio unit testing framework and helps out with TDD
QUnit addon to run multiple test suites from a single file.
Adds mocking capabilities to the LightInject service container.
The Moq.FSharp.Extensions provide extension methods and functions to enhance the Moq experience in F#.
An automocker for FakeItEasy. Can mock concerete dependencies as well as interfaces.
A web browser replacement for testing websites without the browser overhead.
FsMocks, a mocking library for F#
An utility library which extends xUnit framework
An extension to the LightInject service container that enables dependency injection in xUnit test methods.
Setup and teardown of service resources in unit testing and integration testing.
Setup http client resources
Help features for test driving EPiServer CMS and Commerce
A simple package to speed up the assertion of parameters of methods mocked with Moq
A library for unit testing Serilog log events in concurrent testing frameworks.
Support for unit testing of libraries based on the re-linq SQL Backend.
Unlocks types and methods loaded into a managed process for dynamic overriding (mocking)
An opinionated helper adding syntaxic sugar around Moq library
A fixture for XUnit that start up a fake local S3 bucket to test your code with. Whilst it was built for XUnit it should be framework agnostic.