Top 20 NuGet assertion Packages
A simple package with guard clause helper methods. See docs for how to extend using your own extension methods.
Generalized assertion library, covering argument, operation, and unit test assertions.
CodeJam is a set of handy reusable .NET components that can simplify your daily work and save your time when you copy and paste your favorite helper methods and classes from one project to another.
Testify is a unit test assertions, test data creation and contract verification framework. It's not dependent on any specific unit testing framework.
A simple diff comparison asserter that makes it easy to assert if two texts (strings) are equal, and display the differences in a diff tool if they are not. Simply put it is a much simpler (and dumber) version of ApprovalTests that should get the job done for simple scenarios. You can easily create ...
A collection of xUnit.net assertions, tailored for Tiger libraries. (As source.)