NSubstitute is a friendly substitute for .NET mocking frameworks. It has a simple, succinct syntax to help developers write clearer tests. NSubstitute is designed for Arrange-Act-Assert (AAA) testing and with Test Driven Development (TDD) in mind.
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.
Pester provides a framework for running BDD style Tests to execute and validate PowerShell commands inside of PowerShell and offers a powerful set of Mocking Functions that allow tests to mimic and mock the functionality of any command inside of a piece of PowerShell code being tested. Pester tests ...
Rhino Mocks is using Castle Dynamic Proxy (http://www.castleproject.org/dynamicproxy/index.html) to handle proxying the types it needs to mock.
The Dynamic Proxy project has been invaluable resource and made creating Rhino Mocks possible.